Ram failure correctly identified?

Running:
Dell Inspiron 1720
Core 2 Duo T8300 (2.4ghz)
3gb DDR2 ram (1x1gb, 1x2gb)
GeForce 8600MGT
Windows Vista

Hi everyone,
I was hoping you could spare a minute to give me some advice. Last night, with no warning, I could no longer boot Windows. I got erratic results on each attempt. Sometimes a blank screen would display with only my cursor, sometimes the "safe mode" selection screen would appear, sometimes kernel panic. I was getting memory errors like "no physical memory at the location required for the boot manager" as well. The Dell diagnostics on the invisible partition said that the ram in slot A (the 2gb stick) was faulty. So I tried these combinations, none of which resulted in me being able to boot Windows:
-Switched the 1gb and 2gb sticks into the opposite slots (no change)
-Took out the 2gb stick, leaving only the 1gb stick (can load the bios, run diagnostics like memtest86, run linux livecds)
-Took out the 1gb stick, leaving only the 2 gb stick (can't even load the bios this way)
-Tried to boot with no sticks (least successful!)

Ultimately, I was able reformat and reinstall Windows using only the 1gb stick. Here's where I get confused:

I don't know what I'm doing, is there something I am not seeing or forgetting to account for?

What caused the 2gb stick to fail suddenly? I wasn't having app crashes or anything, and in addition, it failed so totally that when left alone in the machine, the bios can't even load.

Why did the failure of one of the DIMMs totally trash my Windows install? How can that even happen? Even with the one good stick alone in the machine, I would still get kernel panics when I tried to boot. I moved the 1gb stick between the slots to no avail.

Is it possible that slot A (the previous home of the bad stick) is somehow corrupt, and will eat my healthy DIMM (and any replacement ram) now that it's in that slot?

Any help is appreciated. Thanks.