There were 2 STOP 0x3b minidumps - the rest (14) were of the STOP 0x124 variety.
Unfortunately, there's nothing specific in any of them, so it's back to the old-fashioned way (updating drivers). I will be very interested in the progress here - as it will tend to prove/disprove my thoughts about drivers causing STOP 0x124 errors.
Here's a list of outdated drivers that you should update. No guarantees that this'll fix it, but I'd suspect that it was chipset, video, networking, or audio drivers (because both of the STOP 0x3b errors happened while playing a game).
Make sure that you update with 64 bit drivers - especially the Netgear USB wireless, that's essential! If you can't locate them, post back for us to have a look.
Code:
RTKVHD64.sys Wed Dec 12 05:56:26 2007 Realtek High Definition Audio
rtlprot.sys Fri Apr 20 05:16:48 2007 Realtek WLAN
wg111v3.sys Fri Dec 28 01:59:29 2007 NETGEAR WG111v3 54Mbps Wireless USB
nvstor.sys Wed Jun 06 16:34:00 2007 NVIDIA nForce(TM) SATA Driver
EDIT: Just a thought, but are you using both the wired and the wireless connection at the same time?