In 2008 server you have the new group policy options to play with. Look under - User config -Preferences - Control Panel Settings - Internet Settings. RIght click new (choose ie version) then enter your homepage(s) in. Hit the last tab - common - tick item-level targeting and press the targeting button.
From here you can define what this policy applies to e.g.
New Item - security group - select domain users -ok
then to exclude individuals
New Item - user - select user account then hit - item options and change to 'is not'
Your xp and vista clients will need the group policy client side update installed
http://support.microsoft.com/kb/943729