I'm not a big PC shopper except for watching the Sunday CC, Best Buy & OfficeMax advertisements. I've seen their Celeron 'bundles' lately on sale for as low as $249 *after rebates*. Yeah, a bit more than Hoagies, but 40 or 60gb HD, 2.8 Ghz, 256k ram, probably better L2 cache than that old skool optiplex. Plus it's brand new with warranty.
10 gig HD really isn't that big. I dunno how much space Windows 2000 pro takes up, but XP is about 3-4 gig depending on your installation. That would leave you with maybe 6-7 gig not counting any partitioned backup. I'd hold out for a bigger HD, more ram and faster processor for the extra $100 or so bucks (plus you get a crappy monitor and printer to boot!).

I guess if you were on a tight budget that $139 refurb'd Dell could be attractive.