I use my two main machines at the same time. On the right I have my Acer Aspire 1691WLMi.
512MB RAM
128MB Shared Intel Extreme Integrated graphics
80GB HDD in two 40GB partitions
DVD+/-R slotloading drive
1.6GHz Pentium M
Windows XP Home Edition
15.4" widescreen glossy LCD, 1280x800

On the left I have my Beige G3 DT:
256MB RAM
6MB VRAM
40GB HDD
DVD-R
266MHz PPC 750
Mac OS 9.22
17" CRT, 1280x1024

I use the Acer for internet, games, and skype. I use the G3 for iTunes and IRC usually. And occasionally a few web pages.