I 'upgraded' my webserver (meaning I have a whole new machine and am discarding the ancient pile of metal that is the old webserver) which is running CentOS 5. This means it's PHP5 and MySQL 5 and High5s.

One cautionary note:

When I installed the server, the clock was 8 hours fast. I didn't realize this right away, so I fixed it.

An interesting side effect is that because my Drupal files had filedates in the future, APC refused to cache them. I spent quite awhile pounding my head against APC, only to find that, the next day, everything was working just fine. Go figure. This may or may not come up for some few of you someday, so remember this tiny little factoid.