It looks like the windows drivers might be an option, too.
The rt2500usb drivers on the CD that came with my card seem to work OK in and older 3.4.3 SimplyMEPIS I'm in right this minute.
Here is all it took (I just copied the drivers to my desktop to install them) and link quality shows at 100/100 with my rt2570 based Belkin USB Wireless G adapter. You might need to remove/blacklist any drivers in it that conflict first to use it.
root@1[Desktop]# ndiswrapper -i rt2500usb.inf
Installing rt2500usb
root@1[Desktop]# ndiswrapper -m
Adding "alias wlan0 ndiswrapper" to /etc/modprobe.d/ndiswrapper
root@1[Desktop]# modprobe -r ndiswrapper
root@1[Desktop]# modprobe ndiswrapper
root@1[Desktop]# iwconfig
lo no wireless extensions.
eth0 no wireless extensions.
wlan0 IEEE 802.11g ESSID:"cockfield" Nickname:"default"
Mode:Managed Frequency:2.437 GHz Access Point: 00:13:10:03:23:A9
Bit Rate=54 Mb/s Tx-Power:20 dBm Sensitivity=-121 dBm
RTS thr=2347 B Fragment thr=2346 B
Encryption key:off
Power Management:off
Link Quality:100/100 Signal level:-60 dBm Noise level:-256 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
root@1[Desktop]# dhclient wlan0
Internet Systems Consortium DHCP Client V3.0.3
Copyright 2004-2005 Internet Systems Consortium.
All rights reserved.
For info, please visit
http://www.isc.org/products/DHCPListening on LPF/wlan0/00:11:50:8a:33:83
Sending on LPF/wlan0/00:11:50:8a:33:83
Sending on Socket/fallback
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 8
DHCPOFFER from 192.168.1.1
DHCPREQUEST on wlan0 to 255.255.255.255 port 67
DHCPACK from 192.168.1.1
bound to 192.168.1.101 -- renewal in 35480 seconds.