How 'bout my 9-year-old Dell?
I'd use that for Windoze... Win '98, yo! It's the oldest peecee I've got with me. Plus, I need to use FireFox or something for Hotmail, as I can't get it to render properly with IE5 or iCab.
For Macs, I've got my 540c running 7.5.5. I'll be spending most of my time with that little bugger, including posting my progress. An added project would be to rebuild 3 batteries so that I can use it for more than five minutes without its duct-taped power adapter. For emergency use (such as eBay bid sniping), I shall use 8.6 on a 233MHz WallStreet.