Ok.... First post here on Toms Hardware so dont bash too hard if it is a dumb question ;-)
 
Im building a PC in about a month and im currently spec'ing it out. I am pretty out of the loop when it comes to hardware these days. The last time i built a PC was with a P4 2.4GHz 800mhz FSB and it was top of the line at that time so you get the idea. Anyhow, i've been reading a lot lately on all of the stuff out right now and i've decided to go with the 8800GTS 512mb card for my GPU. The build is extremely incomplete, but i do know a few things: i'll be going with an Q6600, 4gb RAM (2x2gb, Dont know type or brand yet), SLI ready mobo (again dont know what brand/type), the rest doesnt really matter i guess... Planning to build for around $600-$700 range.  
 
Question is whether or not its better to get a stock GPU if i plan to OC the system myself, or go for a factory OC'd version like an EVGA card (http://www.newegg.com/Product/Prod [...] 6814130325) to OC? Not really sure if its a bad idea to OC an already OC'd card, or if it is better or what. Thanks for the help.

No. Since they did not add an aftermarket cooler, or do any kind of hardware modding, that factory oc is just an oc, and nothing else. You can do it yourself for the same results.

There is no difference in a stock or OCed card. Only that the factory OCed card is flashed with a higher clock speed. That's all.  Granted the cards that come with a better cooler usually ARE factory OCed, some OCed cards still have the stock cooler.  I personally like the 8800GT's that have the better cooling.. A GTS already has great stock cooling.

BTW: my 8800GTS is a stock card and I cranked it up to 750 without breaking a sweat.  It can go higher but it was a nice round stable number.