I'll add another site to the "good XOOPS host" list : Linksky
Lots of features and unmetered bandwidth, and I've never had a major problem with them. Very inexpensive - They have hosting plans as low as $5/month. I've hosted a PostNuke site there for years, and I've recommended them to multiple friends and clients. Just installed XOOPS on a LinkSky hosted domain for a client, had no problems (Xoops is available from their cPanel/Fantastico applications).

If you do sign up, specify that you were referred by "hillsidedrive.com" - I'll get a free month (about $8 value).