Will a 7800 GS bottleneck with my system?

I have an Asus P4C800 Deluxe, P4 2.6 ghz, (2x1gb) OCZ Enhanced Latency. and a 400 watt Antec PSU. Please, only respond if you really know what you're talking about with bottlenecking. It seems like there's alot a mix responses when it comes to this topic. I know the main thing that will be analyzed is my CPU. Though, from what I've surmised, the isn't a huge limiting factor in pulling the FPS in video games, seeing as how the video card and RAM seem to be the two most important. I've found the 7800 GS for $265 after shipping and decided to go ahead and opt in on this deal as long as it get bottlenecked. Also, I was wondering if a possible price drop of the 6800 GS AGP or 7800 GS would come into effect anytime soon. Finally, if not a 7800 GS, how would a 6800 GS fare?

what resolution would you be playing at?

Yes, the res u'll be playing at.. or else it'll be difficult to tell.. :)

Probably make little diff if <=1280x1024. A 6600GT will run most games at 1600x1200 fine, a 6800GS/7800GS will be damn fine :)

To answer the original question, the 7800 will bottleneck the system (in all but the most unusual of situations anyway). You ideally want to get a graphics card that will match the rest of your syste, UNLESS you want to keep the graphics card after upgrading the rest of it. That said, you are clearly looking at AGP, and so future upgrades will be unlikely.
I had a GeForce 6800 (12 pipe vanilla) and the difference using that between a P4 2.6 and an Opteron (running at 2.6Ghz) was increadible - the P4 really held it back, so a 7800GS will be really, really held back.