Sorry Jack,
but this is probably the 10th time someone posted this question during the last two or three months. Just do a search for cluster 2005 2000 on this site.
Yes, you can have SQL 2000 and 2005 coexisting on the same cluster. There are no specific issues with such an install that I'm aware of. We had 10 2000 instances and 7 2005 64-bit instances on one cluster without any problems.
Markus
[font="Verdana"]Markus Bohse[/font]