3-400 pounds every year? You must be doing something wrong. Nowadays, PC+console multiplatform releases means games are more forgiving when it comes to old video cards than ever. I can run Mass Effect 2 at a graphical level that is very close to what the XB360 outputs, and I bought this 8800 GT video card for £100 over two years ago.
But of course, if you insist on your PC games looking 10 times better than the same games do on a console, then I suppose you also have to pay extra for that.
-edit-
Actually, I just took a screenshot of a scene with a fair amount of 3D models and stuff. This runs at about a 40% higher resolution than the game runs at on Xb360, and I'm getting a framerate of about 50 fps there. On 360, the game is capped at 30 FPS, but sometimes dips a few frames below that. Framerates as low as 30 are very rare on my PC.
I'm not running the game with antialiasing on, the 360 version doesn't use that anyway. I did however run ME1 with 4x AA and had very few problems with that.