Ilya is right. I know that http://www.site5.com says to offer 10 gigs a month. You may want to check them out. Try using http://www.hostreview.com (i think) and see what shows up. If ya get much bigger you may have to go dedicated >:0)
I recomend seeing flycast or burstnet about posting ads on this site. No harm in bringing in some money for yourself to pay for the hosting.
Donate to UBBDev today to help aid in Operational, Server and Script Maintenance, and Development costs.
Please also see our parent organization VNC Web Services if you're in the need of a new UBB.threads Install or Upgrade, Site/Server Migrations, or Security and Coding Services.
