That's an odd one since Adobe is a cross platform reader.
http://www.adobe.com/products/reader...dex.html#80win
If you go to download a manual for a board often you will get the prompt to download the latest version. The latest release for Vista is found at
http://www.adobe.com/products/acrobat/readstep2.html
The Aspell wouldn't install on Vista when tried. You would have to see if that will go on XP there. At least in XP you can easily remove IE 7 in the control panel's add/remove>add/remove Windows Components section there to go back to IE 6 or try reinstalling 7 to see if that will allow ieSpell to work then.