Clarification on 4G memory with Windows XP Pro: Kernel will use 2G for itself, paging, etc Applications can use the other 2G (total among them) You can 'tweek' BOOT.INI with the /3GB switch, which will adjust the Kernal to 1G and Applications to 3G, but in my experience this degrades overall performance.
You don't really give a lot of information, but let's have a look. I guess this is the one with 800 MHz front side bus, and not an older model. Xeon processors are usually for servers, and they are not very used. As far as I know the advantage of the Xeon processor is that can be used in multiprocessor configuration, and you can use 2 of them on the same motherboard. That rocks. It should be possible to get it at faster frequencies, though RAM is always good, although 4 GB might be more than you need. What you have to check is the speed. If I'm correct you should have PC3200 in dual channel configuration this is also a lot. Here you have to check, besides the rotation speed (but it won't be more than 7200, I'm afraid), the interface. The best is SATA 2 or SATA 300, but you should have at least SATA 150 This doesn't seem to be great, but you don't play games, so it should be enough. Apparently this is for 2 displays. Do you have 2 of them? it looks pretty good, although you are probably going to have more a server than a workstation; for computation intensive tasks it might be not the best. It depends on what you have to do. If you don't buy a machine from a big manufacturer you should also make sure that the components inside (motherboard, memoty, video card, etc) are of a good quality, but considering the level I don't think it's an issue Also, I assume you will have some sensitive data. To make some backups you can use the CD/DVD writer that you are *surely* going to get, but if you want really a cool solution check if you can get a couple of hard disks in a RAID. In that way whatever you save will be automatically copied.
What analysis software will you be using? The computer should do fine for your general specs, but most will. I'd tell you look to eBay and grab yourself more machine than you can elsewhere. I'd say you could use the server edition of MS (2000 or 2003) and max out your RAM. Server's also give you access to SCSI drives and there's added reliability there. You introduce the ability for true hot swapping and a lot of other creative possibilities. You'll bring into play many multi-processor possibilities also. I love my quad processor 16 gig Dell setups. And not a one of them cost me over $1,000 with their massive drive setups. My personal preference would also lead me to have you look at Dell as they have a more beginner friendly tech support staff. They always have gone the extra mile for many of my clients. Good luck!