IMO it's actually allot easier getting a Mac to incorporate into a PC
based wireless network than the other way around. I would suggest a
Linksys, Netgear or D-Link Wi-FI router rather than the Base Station
(they are not intuitive at all!) Follow the instructions that come with
the device to set it up (through a network cable) and then use Mac help
to connect the iMac wirelessly. There is plenty of documentation out
there to help you eg.
http://www.geocities.com/onlinesoftw.../wireless1.htm
If you do choose to use a Geek, don't let them charge you anymore than
an hour for it!!
Good Luck