Too Small to Read

I currently dual-boot into either Windows XP- or Vista. I subscribe to
several email newsletters that are sent with html content. One example is ZNET’s Ed Bott’s letter.

Under my WindowsXP settings I can view this fine- but under Vista, it is too small for me to read!

DPI settings (Control Panel->Display-Advanced) are identical

I think this is a IE 7 issue, but am not sure. IE Text size (View->Text Size) is set to Larger in both. I also have tried both Eudora and Outlook to read emails- same issue: html is too small for me to easily read in Vista.

Any ideas? Thanks