Odds are, with a Dell, there will be very little you can do via the BIOS to tweak timings and such. All of that stuff is pretty well locked out. That's the bad news.
The good news is that it's gonna be an Intel chipset-based system, so PCI bus latency is not going to be a big issue. Also, it's quite possible that your video card will come with a software overclocking tool that will let you speed up the card's performance as much as possible. Odds are that, compared to a "shared system RAM" video system, which a lot of the Dell 2300's have, your PCI video system will be smokin'.