Of course bootcamp and running native Windows is the best solution, but if you must run both at the same time pick VMware Fusion 1.1.1 over Parellels because it has support for 3D via shader model 2 and Direct-X 9.0, although deemed "experimental" even in this stable release.
The lastest beta for the 2.0 series is
available here but remember this is not a stable release yet and all the usual concerns, cautions and warnings apply for that kind of software, but it looks VERY promising.
-jim