BSOD error...would like a nod in the right direction

Been getting a very annoying, completely random BSOD.
Here's the description...
BCCode : 1000000a BCP1 : 00100004 BCP2 : 0000001C BCP3 : 00000001
BCP4 : 804E2551 OSVer : 5_1_2600 SP : 2_0 Product : 768_1
It's the same everytime. I've followed the guidelines (memtest, check PSU, cooling, etc) and am none-the-wiser. Maybe it's a driver thing.
Anyway - if someone could take a quick look at my minidumps and just point me in the right direction I'd be very much obliged.
Thank You.

The first three minidumps are crashed at timer routine. The last minidump is crashed with memory corruption. They are the signs of faulty ram. Run memtest to stress test the ram.


Debug report
Mini042506-01.dmp BugCheck 1000000A, {100004, 1c, 1, 804e2551}
Probably caused by : win32k.sys ( win32k!RawInputThread+4f3 )

Mini042606-01.dmp BugCheck 1000000A, {100004, 1c, 1, 804e2551}
Probably caused by : ntkrnlmp.exe ( nt!KeReleaseQueuedSpinLockFromDpcLevel+1d )

Mini042606-02.dmp BugCheck 1000000A, {100004, 1c, 1, 804e2551}
Probably caused by : ntkrnlmp.exe ( nt!KeReleaseQueuedSpinLockFromDpcLevel+1d )

Mini042606-03.dmp BugCheck 1000008E, {c0000005, b82f979e, b5d0ab54, 0}
Probably caused by : vsdatant.sys ( vsdatant+3e79e ) <-- Crash due to memory corruption

Thank's very much for looking into my problem.
I've tested my RAM with Memtest andMemtest+86 - no errors, though I didswitch my sticks yesterday (and so far no BSODs) and I've yet to test them individually...
What if Memtest doesn't pick it up? Would you recommend just going out and getting new memory? Could it be just a matter of switching the sticks? (These errors did start when I upgraded my CPU, motherboard, and RAM - though the RAM worked in the old mobo fine...) Sorry to rattle on - I'm just happy to finally have a lead...
Thanks again.