Fast is always the problem, because it take a little bit to get the vid ready
An easy way will be: rip the DVD to your disk and load the riped files into Vegas to convert them into any format you like, even wmv.
A much more cheaper way would be, rip them to your disk, convert them into AVI by using VirtDup and then convert them to WMV by using the Microsoft encoder.
You also could do the same, by using a tool to convert the ripped files into MPEG by using FlaskMPEG for example and encode them afterwards into wmv.