My recommendations to start: don't be cheap! lol This is a lot to consider, but if you want a system to work right, gotta research on what you want, and what you need and don't need.
Get a system with XP pro or media center. Wait at least 10-11 months on Vista yet.
You'll need to do a bit of research on what the game manufacturer recommends and go a little over that. You don't want minimal as your computer will only get outdated faster. Decent system would probably be one that meets the recommendations for Vanguard Hearts, even if you won't play it.
You want a dual core processor (get AMD 3500+ if possable which is close to 3ghz)
Make sure you have a PCI Express 16x graphics card (of a slot to upgrade to one if the mainboard has onboard [built in] video).
1gb ram (2 or more if you insist on Vista)
DvD RW (might as well, they are not much more then CDRW/DVD rom)
150gb or more sata HDD
If you ask for this at a computer shop, have them format the HDD about 50/50% giving you a C drive and D drive. Store MP3's and old game saves on the D drive. That way if windows needs to be formatted and reinstalled, your data will be safe if on the D drive. E-mail from outlook express and other programs like that store the stuff on your C drive by default. You can look threw their help files to learn about backing it up. As for SATA hard drives, they are faster then the older IDE and gaining huge popularity and cost about the same.
Video Cards - you don't need to go overboard on them. Might have to configure your graphical settings to turn off some lighting effects. The game will still play the same for the most part. PCI Express (or PCI-e) cards can be upgraded later if you need to get a lower end one. Again, just go by the recommendations of the game's manufacturer on this.
Vista. First, like all new operating systems give it a year to become stable and support a wide range of hardware and other devices like pda's, mp3 players, phones, printers, etc... If you had a spare system and wanted to toy with it, then it be ok to get. But as your main system, XP will be supported for a few good years yet by Micro$oft and is highly stable. When you want to get Vista, get Ultimate, rest is a waste of money as it lacks too many features, especially Basic and Home Premium. Vista is a ram hog. It requires bare min of 512mb ram. It will run! but like a slug with a broken leg... 1Gb, it will run like xp with 512mb, good enough for forums and runescape... 2gb, it will run pretty good for games. And yes, slugs do not have legs...
You might have to save up a little, but it be worth it. And hardware prices do drop over time. It is best not to be skimpy with a system. Being cheap with computers isn't the best way to go.
As for college life and work with data, make sure you properly back up reports on an online file storage site so if your hard drive dies, your grade won't also. And I've seen a few when I was at trade school suffer from that and half of them ended up repeating the course. Best of luck to ya!