My opinion is this: If you can afford a new machine, it's time to upgrade your system, I would grade your current machine a 4-5 in comparison to todays technology, considering that the newest processors are running at 3.0+Ghz and there are 256Mhz video cards on the market.
  Prices on new machines in the 2.4Ghz range are quite reasonable if you do a little searching, you should be able to find a good setup for well under $1000, and honestly for a 2.4Ghz, depending on what else is included in the package, I would guess more in the $500-$700 range.
  I would think a 2.4Ghz with 512Mb RAM and a 128 Mb video card would serve you quite well for a couple of years.
  I just upgraded to a 2.66Ghz this year and expect to stick with this machine until late 2004 or early 2005, unless I see a really good deal before then.