Hi Kit Austin,
First off, access to your Gmail account shouldn't be affected by the operating system. Try accessing from a different computer and see if you have the same result. My guess is that it is a Gmail issue and will resolved on its own with time.
Since you are able to access the internet at work, but not at home, this may be an issue with your router? Is it compatible with Windows 7? Do you have all the up-to-date drivers? Take a look at these common issues and see if one of the solutions helps you to connect - http://windows.microsoft.com/en-US/windows7/Why-can-t-I-connect-to-the-Internet
Microsoft Windows Outreach