I've asked this before and no one has answered it:What do you loose if you run MOSS 2007 on SQL 2000 SP4?(Aside from a 64bit environment...)
MOSS can take advantage of the new SQL ReportingServices functionality but that requires SQL 2005 SP2.Pretty nifty stuff if you can work it.
I don't think that you "lose" any MOSS 2007 core functionality using SQL 2000,you just gain some SQL functionality using SQL 2K5 (as Mark said).
Speed, security, stability, 2 node single copy clusters unless you buyenterprise, indexing isn't as good, no ms support from aprilLike they say, all the sql stuff.
You would lose some performance, but I don't think you lose anyfunctionality. MOSS2007 was written to take advantage of theperformance enhancements in SQL 2005, but it will run with fullfunctionality on SQL 2000.