I think you need to download an update:
http://www.janome.co.jp/e/e_downloads/software.html
Scroll down to PC Folder. When I clicked on the update page to add Windows 7 compatibiity, I got this:
http://www.janome.co.jp/e/e_download..._pcfolder.html
Some people buy Windows XP laptops on eBay to resolve compatibility issues with software.