The E-ID software you need to run work with your Belgian electronic identity card has been tested on compatibility with Windows 7 32 and 64 bits. The outcome was all green lights so you can now see here (FR) http://eid.belgium.be/fr/Comment_installer_l_eID/Windows/ and here (NL) http://eid.belgium.be/nl/Hoe_installeer_je_de_eID/Windows/ that the software is compatible.
Of course we have many more ISV’s who declared their software compatible. More in fact than was the case at the launch of any previous version of Windows. Here’s a list: