I also have a Belkin 54g wireless router and Virgin as my ISP but I havent had any connection problems.
Log onto the router webpage and check it's event logs for any errors. If none, check the Event Viewer on your PC.
How to get to Event Viewer in XP (if you have this OS):
http://support.microsoft.com/kb/308427
How to get to Event Viewer in Vista (if you have this OS):
http://www.computerperformance.co.uk...ent_viewer.htm
Find any errors and let me know what they are so we can find a solution to the problem.