I have my laptop connected to a wireless router. The wiring goes from the calbe router to the wireless router, and a cable from the wireless to my laptop. .My laptop is running Vista In my living room I have my desktop with a wireless card. I can get on the internet no problem with either card. The desktop is setup for dual boot. When I boot into vista from the living room I can see all the drives and folders I am sharing with the laptop. I can get into them do whatever I want. I can also share the printer. However when I boot into XP, I can not access any of the drives. They show up on my desktop but when I click on them it says unable to access, might not have permissions and so forth. On the laptop I do not have any passwords setup, the network is configured for private, and both computers have the same workgroup name. Any ideas?

Enable a password on both systems, check to make sure desktop XP has same workgroup name. Silence is golden but duct tape is silver

THIS IS ALSO MY PROBLEM IN WINDOWS SERVER 2003, U CAN TRY TO CLOSE THE BOTH FIREWALLS OF WINDOWS AND ANTIVIRUS

Check any firewall enabled on XP and Vista (Windows firewall, antivirus firewall, etc) and then disable them temporary. Try to ping the laptop from desktop with XP loaded, if fail then there is firewall blocking on laptop. Also you might consider to take a look on this simple file sharing article, see whether it helps.