I do not recommend using wireless USB devices. Especially in Win7 systems.
These wireless USB devices have many issues with Win7 - and using Vista drivers with them is almost sure to cause a BSOD.
Should you want to keep using these devices, be sure to have Win7 drivers - DO NOT use Vista drivers!!!
An installable wireless PCI/PCIe card that's plugged into your motherboard is much more robust, reliable, and powerful.