I'm thinking about knocking together a Solaris box at home to act as a combination server and learning exercise.

What are the minimum hardware specs I can throw at it such that it'll be actually usable? I'd be cobbling the machine together from a stack of various x86 PC spares/leftovers. Does anyone have experience with Solaris at the lower end of the spectrum? The Sun site, for example, claims it'll run with as little as 255 megs of ram, but is it worth the exercise with less than a gig? Will my old Pentium II 450 cut the mustard? (I'm willing to throw a couple of bucks at pricewatch/mwave/newegg on this, but if I need to build a better rig than my main PC, I may not bother.)