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You might want to check Windows 7's hardware compatibility list here: Windows 7 Compatibility: Software Programs & Hardware Devices: Find Updates, Drivers, & Downloads
If you proposed adapter is incompatible, it'll be flagged up on the list......I hope!
Make sure you've disabled your old adapter though and one other thought - have you given consideration to the possibility that your ISP may be having problems in your area? A phone call to find out won't do any harm.