These two easily fit on my home desktop (Dell Inspiron -530 OS XP Professional with Sp-3 2 GB Ram 230 GB disc) and allow me to do just about whatever I want to do with SQL Server:

From Amazon:

Microsoft SQL Server 2008 Developer Edition - Complete package - 1 user - DVD -

Win - English ( E32-00673 ) by MICROSOFT CORP (Windows XP Professional)

1 Used & new from $99.99

Microsoft SQL Server Developer Edition 2005 CD/DVD by Microsoft Software

(CD-ROM - Nov 28, 2005) (Windows 2000 Server / 2003 Server / XP Professional)

Buy new: $49.95 $44.49 27 Used & new from $38.95