Apparently, all incarnations of HTC Wizard except for the i-mate k-jam ship with 802.11g mode enabled. Others, including the original incarnation (Qtek 9100) come with only 802.11b enabled.
To fix this, add dword 'dot11SupportedRateMaskG' with decimal value '8' in:
\HKLM\Comm\TNETWLN1\Parms\
Then soft reset.