I am a great believer in if you need it now, buy it now. Technology will change the day after you buy a computer or peripheral anyway.
I have an Airport Extreme which feeds an iMac, iBook, a PC and a wireless printer. I have had this set-up for one year and it works flawlessly. After a power outage once I had to reboot the Airport.
So far as security is concerned I have a neighbour who openly admits to trying to break into my network but is unable to.
So, for reliability and security I have no hesitation recommending the Airport Extreme.
BTW there is still disagreement on the next wi-fi standard (802.11.n) so I think that buying an 802.11.g router will be safest for the time being.
Gp