My Ti 4200 SUCKED. do NOT buy one of those.
If you wanna pump some cash into other things like the mobo or processor, the 9600 Pro is a pretty sick card (its been awesome for me so far), although a 9500 pro is the same card with 8 pipelines opposed to 4 (if you know what you're doing, that is). I'm definitely sticking with ATI from now on. I've had bad luck with nVidia cards. The whole reason I bought the 9600 pro was due to my geforce 4 getting fried after 8 months of use (never overclocked it).
I agree with Gond, I have two WD hard drives - never had any problems.
I'd say go with an AMD processor. My 1 ghz athlon xp went faster than my 2 ghz pentium 4. Although, that might just be windows; I had Redhat 7.3 on my AMD box.