Okay, thanks for that information about the antennas. While it's not beyond the possibility that stray RF can affect the system, I've not heard (so far) that installing internal antennas can lead to what you are experiencing.
The SP3 update is finally over. Apparently I'm now good for 30 days until I need to "activate" Windows. The 600X is still very responsive, ignoring the occasional missed keypress. I don't know if it's because I haven't used the system in some time or if the OS is getting hung up for a split second (I'm voting for the first reason). I've got several .MP3 files queued up in Winamp (5.08c, a really old version) while I'm typing this up and so far it's been working fine.
I think I'll take this 600X to work today and let it run all day.
(I really missed the feeling of this keyboard)
edit: 1pm PDT The 600X has been running on my desk here at work for a couple of hours. Firefox has at least three tabs open at all times; My Yahoo, the forum and AOL Mail. This way I'm constantly using the wireless to download Flash ads
. I've checked the IRQ usage and most of the peripherals are also using IRQ11. I think this is pretty much the standard setup. If you are still getting freezes while using a PCMCIA wireless card, then I'd have to say that it's probably not a wireless problem. If you think that it may be related to SpeedStep, then check your Windows Power Manager settings and see if you can set the system to "maximum performance". I think that should keep the system from dropping to the lower speed. You can also try disconnecting the battery and run the laptop on just the AC. That essentially will duplicate what I'm running at the moment and it will probably also force the CPU at the lower speed.
Well that was interesting.... as I was typing those last few sentences, I got a sense of what you might be seeing. The system appeared to ignore my typing but Winamp was still playing. I looked at the wireless icon and it was transferring data. The Trackpoint was not moving smoothly. I was able to launch Task Manager and saw that the CPU usage was near 100%. It looks like a Windows system update is running (update.exe), as well as AVG (Free 8.5) eating up CPU cycles.
This lasted about 5 minutes. 26 Windows updates are now waiting to be installed. The system is back to being responsive as before.