The Hx4700 use the TI ACX100 (802.11b :s) and the driver ported for it is decent... much better than the same driver used in the HTC BA and HTC Uni, which essentially have the same card (although the Uni uses an od hacked 16 bit slave mem driver whereas the Hx4700 and the BA are SDIO -- the r3verse engin33red driver was meant for SDIO).
Either way, it's <still> 802.11b, and the range kinda sucks. You could use a pcmia sleeve and use better cards, but you'd lose out on the SD card install option.
Another thing is the fact that Angstrom <sucks> ... so the only real way to run BT apps is to botstrap a Debian install on an SD card partition (as it won't fit on the tiny flash ROM.
Go with an Openmoko Freerunner if anything. I started a project entitled Neopwn with the same intent, and it has the ability to support USB WLAN cards... porting the drivers was a PITA, so have plenty of time to spare.