Best Practice? SQL 2000 and 2005 on same server

(I tried to search for answers before posting, but had difficulty)

I have read in Microsoft forums that you "can" install SQL 2005 as an instance on a SQL 2000 server (not clustered.)

My decade+ of experience tells me it would be a bad idea, I'd expect the next service pack to fail or some other un-expected result. This is for a high availability application where the vendor requires SQL2000, and our custom coders want to use some SQL2005 featuers.

Does anyone have experience with two instances of different versions in a high visibility production system?

Does anyone have some points I could use to argue against this other than me sounding paranoid.

Thanks!I just completed a seminar that was hosted by Michael Hotek, author and MVP. He stated that SQL Server 2000 and 2005 (non-beta) can reside the same server with no problems for the 32 bit products. For 64 bit, there's a specific order to install both for both to function properly...but since you're probably talking about 32 bit, I won't get into that.|||I've been running the two side-by-side for many months on dev and test machines, atlhough not in production. I don't know of any problems with running them on the same machine (but I haven't tested every possible configuration either).

-PatPsql