The first Witcher game was built on a heavily modified Aurora Engine (KOTOR and Neverwinters Night 2) so it is a PC ass PC game. If you don't have CRPG experience, I would just wait for Witcher 2 on the 360.
I was in the same boat. I bought the original in 2005, played it awhile but lost interest. I just came back a few months ago and tried to recover my account. The customer support was really helpful. I didn't have any of my information, but they gave me the benefit of the doubt. I would say try anyways. Your '05 character will have some pretty cool anniversary gifts waiting you can sell for gold in game or "import" into GW2.
After getting my character back I bought the trilogy along with the Eye of the North and I'm having a good time. It starts off slow but a quarter the way through you can jump ahead in content and get powerful hero characters you weren't meant to have in Prophecies and Factions making the game super easy. The game can be played in chunks so I come back and do a mission every few days. I say as long as you play casually it can be a good time.