As long as the type of Wifi is the same, you have should have no problem with using another companies wifi card. If you have 802.11b set up at home, any 802.11b card will work. As for sniffing software I'd recommend Mini stumbler(I'm not sure if it works with ppc2003, but it should). http://www.netstumbler.com/download.php?op=viewdownload&cid=1&orderby=hitsD
Only problem with mini stumbler is it really only works with Orinioco cards or cards with the same chipset. You can also try (i have not used these though) http://www.airscanner.com/ It may not work with PPC2003 but the version that does work with PPC2k3 may be out, I'm not sure.
For info on ministumbler - http://www.stumbler.net/readme/readme_Mini_0_3_23.html