Sorry for your issue, couple things to I need to know:
When you were using vista, did you have to use static ip as well? Not sure how old your router is, but some routers can't handle the dhcp broad cast flag (this happens for vista, I am sure the same goes for Windows 7). To handle the flag issue you have to do some registry editing. We will get to that, if necessary.
I assume you are using the drivers
assigned by windows. If so, you should get the drivers from your manufacturer's website, and update the drivers with theirs.
You may run into the issue where it may not let you update the drivers by telling that the latest one is already installed. Use this method to update the driver
Device Manager, the Wireless Card, Update Driver, Browse computer, pick from a list, Have Disk, then locate the unpacked folder with your drivers. if there is isnt a w764, try the xp64 driver.