I really believe far too many people out there have far more power on their desk than they really need, and if you take MS resource hogs off the system, well, even more of that power sits around not being used (thus the distributed systems for cracking codes and doing SETI analysis). I ran xemacs and netscape 3 on a 75MHz with 16 mb of ram while telnetting and compiling code, and it was quite comfortable. I can't remember when i increased my memory (there's something mildly amusing about that sentence), but it was my spouse running photoshop who needed the memory, not me. I also had a 500 MB partition. It was close, but i stored much of my data on zip disks. (NOTE: biiiiig mistake.) Monte carlos amd other data analysis went smoothly.
Memory would be the first thing I'd suggest you'd upgrade. I suspect you could find 16 MB easily in a machine someone is throwing out. As soon as you start thinking about the GIMP or playing with sound clips you'll probably want a bigger HD. Just my two cents, judith