I run a ton of Wordpress blogs and have had a ton of problems with hosts not properly setting up Linux to host them.
These guys have their own mix of Debian Linux and it works flawlessly... I went from a server load of 2.x to 3.x to less than 1!
Read about it at:
http://www.virgins19.com/webmasters
relevant info starts with: Is your Wordpress blog killing your virtual hosting server?