For the benefit of everyone here, I'll take a moment and outline which graphics settings I use in TF2, what they mean, and why I set them that way. I'm running a system with 2gigs of ram and a Geforce 7800GT video card - very middle of the road.
Resolution: 1280x1024 - determines the number of pixels your screen will display. Ideally, you should start at the default or 'native' resolution supported by your monitor, which for a full-screen box-shaped monitor (as opposed to widescreen) that's usually 1280x1024. Widescreen monitors vary quite a bit depending on how big it is. If you have large and consistent slowdowns, you might start with lowering this setting.
Texture quality: medium - determines the SIZE, in pixels, of the pictures applied to the models inside the world. The higher this goes the more demands the game will make on your video card's memory and the bandwidth of your card's bus.
Model detail: High - Controls the number of polygons and animation details used for characters, weapons, and other items within the world. Turning this down will make your guns look more boxy, and I notice in TF2 that it disables the facial expressions and makes the characters look goofy (especially the heavy, who looks like a psychopath) - eats up more processor and more video card power, but generally keep it high as most video cards are optimized to handle very high polygon counts.
Shadow detail: High - On high, character models are completely re-rendered in black and projected on the ground to give you realistic playing-in-the-sun shadows. Lower settings give either boxy blobs or just a black dot underneath characters. Occasionally, that high shadow setting might let you see someone around a corner - or if your system glitches like mine, you can see them through the ceiling above you. again, eats up some video card power
Shader detail: High - Things like the pyro's flame, the trail leading off of rockets, explosions, and especially water effects will be rendered with more loving care. Can eat up a lot more video card power on high settings. You will also notice more depth in corrugated walls and things like that where shader tricks have been used to add depth.
Color correction: Recommended setting - adjusts colors in a scene to make them more picturesque - not something i deem terribly necessary in a multiplayer combat game, but i'll do what valve tells me to do here - doesn't affect performance
Anti-aliasing: I'm using 2xMSAA - Anti-aliasing blurs the lines of edges to make them smoother and more realistic. Back in the day, we used to crank our resolutions ever higher in pursuit of "no more jaggies!" AA makes jagged lines a thing of the past, but I only use it in certain games. TF2 was designed with AA in mind, so it looks much better and operates fine. Counter-Strike was released when AS was fairly new, so I don't use it and it runs much better. MS stands for multisampling, if you have a GeForce 8 or higher you can use CSAA and you should, it's much faster. There's also CFAA which is best but only on newest cards. You just have to play around with this one to find a setting you like, but if you're having slowdowns, it's better to switch it off rather than go to a lower setting - 16xCSAA will be a lot faster than 4xMSAA, as it's less intensive on your processor.
Filtering mode: 8x Anisotropic - if you look at textures with hard angles in them, like warning stripes on the ground, you'll notice they distort pretty badly as they run into the far distance. The higher the level of filtering, the better this is corrected. Makes for a bit of a performance hit on your graphics card, but not one that I think is noticeable.
wait for VSync - just turn it off. if the momentary 'tears' in your screen are really bugging you, because the game is running THAT FAST, then you can go ahead, but all this does is limits the game to frame rates which are equal increments of your screen's refresh rate. IE, your game will be locked at 60, 30, 15, or 12 frames per second. When it could be running at a dandy 42. It's a stupid setting for practical use.
HDR and Use Bloom when available: these are essentially the same thing... HDR will put more strain on your system than just bloom, but you'll hardly notice the difference between the two. HDR (High Dynamic Range lighting) emulates the naturally limited range of contrast our eyes can see, and in dark locations shifts the spectrum of light down as if our eyes had adjusted. Then, when entering full light, everything will be washed out and bright until our 'eyes' adjust again and the spectrum shifts back into place. HDR is the highest setting, Bloom is the middle, both of them off is best for performance.
Motion blur: gimme a break. Ever play GTA3 on a PC and try switching the cinema blur off? This is the same thing, but VERY VERY slight. Turning it on makes it look more like the XBOX version of the game, turning it off will offer you crisp and clear focus no matter how fast things are moving and therefore you should be better able to see.
multithreaded processing: turn this OFF unless you know what you're getting into! it's a beta-testing feature which can offer a 20fps boost if you have the right processor, on my old system it made for occasional slowdowns and even when the performance was up, I could notice a distinct jitter in the game that wasn't there before.
tl;dr - the settings I'm using:
Texture detail: medium
Model detail: high
Shadow detail: high
Shader detail: high
Reflections: reflect world
Wait for VSync: off
color correction: the recommended setting
motion blur: off
multithreading: off unless you have a modern triple or quad core processor, unlike me
i got a lot of this information from HERE.
Final thoughts: "Computers are for people who know how to use computers!"
You must be THIS nerdy to play games made by Valve!