iMac 20inch 2gHz Intel Core Duo 2GB OS X Version 10.4.11

Not a major problem but I've noticed for the last couple of months (eversince I updated my mac software) the airport icon in the top right hand side of the screen fluctuates from on (full signal) to off (zero signal) then back to on periodically, perhaps every 2 minutes.

I don't have this problem with my windows machines so it's not my router. On my windows pcs i'm getting speeds of 10mb whereas on the mac it's much slower. I feel this airport issue is responsible for slowing it down, however my internet never completely cuts out when the airport icon is at nil.

What do you suggest I do? Would restoring the airport software back to the previous version be the simple solution? How do I go about doing this?

Thanks in anticipation,