So I bought a GTS250 and have a new 500W PSU to go into it, and I was wondering if the processor would bottleneck. I might be able to overclock it, but it is a stock Gateway, and have no idea if it will overclock. I am going to upgrade the RAM to at least 3GB, so thats covered. I have a 5570 on order that might be better in there. It is a dual core, but I have no idea of its performance. It runs Vista 32.
The bottleneck will be small if there is one. I ran a Pentium D 945 in our last PC with a GT 240 and didn't experience any problems with a bottleneck. Your a bit slower on the CPU and a bit faster than that on the GPU so I'd say it's probably a wash in most applications. You'll be able to OC your GPU via MSI Afterburner with no problems, but it probably won't yield much of an improvement (maybe 5% more fps at most).
In regards to your CPU's performance, yes it is dual core. Other than that, performance isn't really a word that should be used to describe it. Pentium D's were basically two Pentium 4 CPU's on one chip. They're technological dinosaurs now a days and the achitecture on which they are based turned out to be a dead end for Intel, which is why AMD was considered superior during those days. It's a fine CPU for running a browser or basic home office functionality, but it's defintely not something that should be used for any sort of modern gaming.
I was suspecting the GPU would bottleneck because I have one on my Athlon 64 4200+ X2, and when I play any game it runs great, but when it comes to higher end games (BFBC2 and more CPU intensive) the processor hits its max before the graphics does. The GTS250 was $40, so I found it to be a steal since I have a capable PSU already. If it were to play anything, it would be lower end games like LoL. Were planning on using it as a spare LAN rig for LoL and the other games we mostly play. Thanks for the help!