iMac 24" machine - airport signal strength issues

Hi Folks -- I didn't realize we had a non-iPhone Mac help group here :) This is awesome.

Anyway, I have a new 24" iMac, stock machine (2.8Gig, 2Gigs ram, 320Gig HD). No mods. I have wifi in my house (Linksys WRGT with DDWRT), working seamlessly with:

Lan:
WinXP
PS3

Wifi:
MBP
iMac 20"

Just got a new iMac 24" and it had airport connectivity issues when I first booted it up. I'd get full signal strength upon start up, but within 1 minute of firing up Safari, it'd go down to 2 bars, and basically stall. The 24" is only 15 feet from the wifi, and is sitting where the 20" iMac used to be - so no interference.

It came with 10.5.2 -- I couldn't update, 'cuz I'd lose my connection -- so I d/l'ed 10.5.4 on my other machine and transferred via USB key. Updated, and voila, it fixed the problem. Perfect connectivity.

1 week later (this morning), it had the same problem again. I brought my MBP to the same desk, right beside the 24", and no problems. I logged into the DDWRT and the signal strength to the 24" was fine. Yet still had intermittent signal problems. Argh.

1 hour later, it spontaneously was working fine again.

Argh.

I've google'd and searched the apple support sites, and nada. It's only this machine -- the rest are fine. Actually, this machine is fine too, now.

Help? Comments?

Cheers mates,

Ipecac

Argh -- it's happening again.

My 20" iMac, my iPhones (2G and 3G) and MBP are within 2 feet of this 24" iMac -- the 24" only gets 2 bars and the others get 4.

Any ideas?

Check for software updates from the iMac —*Apple has released firmware updates in the past that address AirPort issues.

Otherwise, I'd bring it to an Apple Store. If the problem has existed since you bought the computer, it may be hardware.

One last thing to try*— back up your DD-WRT config and restore to a stock Linksys firmware temporarily. I know it hurts, but there is a chance it and the iMac's chipset aren't getting along.

That's exactly what I did. I did a software update, including an "airport utility" and it's been working fine ever since. Phew!