I definitely agree with all of the upgrade suggestions, but I would seriously consider the purchase of a new computer opposed to the various upgrades. At the cost of upgrading the hard drive, memory, operating system and possibly adding a CD writer, you can get a pretty robust new computer for about the same price.

To recap the specs

CPU: Pentium III (Any Speed)
Memory: 512 Meg (More is always better, but 512 will work fine)
Hard Drive: 80 or 100 Meg
Video Card: At least 8 Meg of Ram
CD: Writer any Speed
NIC Card: This comes in handy if you want to connect two computers. (All you need is a $9 crossover cable.. no other network stuff is needed)

I have seen computers that closely match the above on Ebay and various discount, or closeout sites. The prices range anywhere from $450 to $700.

Do not worry about the Operating System that comes with the computer. The first thing you should do is change the operation system to windows 2000. Windows 2000 will not have problems managing the memory when rendering large projects.

I hope this is helpful.

John