The last few years I filled in my tax forms electronically using www.TaxOnWeb.be and authenticated using a Token.
You can get a token card quickly (I got it within 2 or 3 days if I recall correctly, but I heard it’s not always that quick 😦 …), and it’s simple to use.
But since I received an electronic ID a few months ago I just acquired an eID reader. I found one from LogOn (found it at 14,95€ and 19,99€ in another shop).
The ReadMe file noted: supports Win 2000 SP4/Win 2003/XP SP2/VISTA 32-bit operating system, but I installed it on a Windows Vista Business 64bit PC without problems.