According to this thread, it's possible to enable 802.11g on the HTC Wizard (so Vario) using a couple of simple registry tweaks. You'll need to register for xda-develops before you can see attached binaries on posts.
I haven't tried this yet – I'm posting this on my iBook and it's somewhat tricky getting activesync running on an Apple machine 
Needless to say, as soon as I get back to my Windows PC (such a long way away, all the way up those stairs) I'll try it.
