I've only bought a couple of pulls but have had good luck with them. The Ebayer has a great rating with only 7 negatives in the last 12 months.
So it's basically your decision from here. There's always a risk when buying a used board, due to the fact that you are dealing with a limited warranty. The fact that the saler offers a 30 day warranty (covers full shipping if DOA and returned within two days) is a bonus. The used boards I bought have only carried a warranty against DOA and had to be returned within 7 days. I think there's a good chance you can squeeze another year out of your system, but you have to decide if it's worth the risk.
As for the board version, there is very little difference in the two version, in fact the manual covers all 1.x versions. Same chipset etc, so you should have no issues with your current OS or the recovery CDs/partition that came with the PC. Version 2.x of the board supports DDR2 instead on DDR1 (not sure if there are other differences)
Keep us posted on your decision and how it works out for you.
