Im really getting frustrated with my fps drops in TF2. Since the SnipervsSpy Stuff in May, my fps drastically dropped from like a constant 60-80 to 25-40 on dx9. Thats not a big problem, but when theres too much action going on in the middle the game begins to stutter. I tried everything to stop it, but even with FPSconfigs that give me 50 more fps, I still get those stutters. Found out that almost evryone that has a similiar rig has the same probs, so next month Im gonna get some money for my birthday so I wanna upgrade my PC. First of all here are my specs

AMD x2 6000+ (2 * 3000 MHZ)
2gb RAM
ATI x1950 PRO 512 MB PCI-e
So I personally think the problem here is the graphics card. Its really old (2006). But I often hear TF2 depends more on the CPU so could that be a reason? I dunno, I personally think the CPU is still fine and only the GPU sucks with TF2.
So if you agree with me that the problem is the graphics card, heres MY suggestion: I wanna change to Nvidia, cause I asked so many people that have none of those fps problems and they all have Nvidia cards so I guess its the better choice.
So what Nvidia card would you suggest? Im not really in to all those Graphic Card numbers so I dont really now whats "teh shiiat" at the moment. Pleaser regard that my budget will be about 150€, if its a REALLY good deal, I would go up to 200€.
Thanks for your help and as usual, sorry for the grammar and spelling mistakes
