Upgrading Dimension 8200 Motherboard- Help?

I'm thinking of upgrading a few components on my Dimension 8200, and I want to ask for opinions on ease and practicality of doing the upgrade as well as what are the actual parts I'd need.

First, I have the 2.0Ghz processor (reports as 1.99 ghz in the bios and device manager, etc) so does that mean I have the 400mhz FSB or the 533? Should I go to look in Bios for the actual FSB speed instead? I know that sometimes when you look for the RDRAM the specifications for what you need changes based on the FSB speed. I was thinking of taking the system up to the max 2GB of memory.

Then, I'd like to upgrade my HD. I'd like to go up to around 320GB, but the 8200's also have a dual disk MB, so I'm wondering can I safely get two 320GB and have them both be read and 'seen' at their full capacity. I just did the microsoft update for SP3 today- and I think I read that not having SP2 is what limited people to the 137GB before? Is there an upper limit to how large a HD these MB's can use? I don't know for sure, but the system board reports as 'Intel Chipset 850', is that the ASUS board? And if so, or if not, how do I find out exactly which board I have?

I'm also thinking of upgrading the video card, though the one I have has done well for what I use it for. I mostly surf the net, word process, etc, but I do play games like Doom3 and Sims2 etc. (medical school doesn't leave much time for stuff like WoW- though I hear it's fun ) Currently, it has the Nvidia GeForce 2 in it, and those games run just fine. What kind of card can I put in it, or can I upgrade the video memory on that card? I don't need something that's gonna do graphic design, but I'd like something that's more current, and hopefully will allow me to go to an LCD monitor as well. Suggestions?

Lastly, I saw a discussion on upgrading the processor on this board, and how the max was a 2.6gHz that would go on the board (assuming mine is the same ASUS board). A quick search on eBay actually yielded this: http://cgi.ebay.com/New-P4-3-06-3-0...ryZ80143QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

and this: http://cgi.ebay.com/Pentium-4-P4-CP...ryZ14293QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

How do I know which I need? Can I keep the fan that's in there now, or should I be looking for a new fan as well?

Ideas/Suggestions?

Thanks!!!