Software/Hardware Questions

Hey, I just bought a 128 MB AGP Xtasy graphics card for my 3 year old computer. I also got a 512 RAM to add into it, and a new 500 wat power supply (Which couldn’t fit in the case :sigh: ).
I was wondering two things, I also got a new copy of Half-Life 2, Game of the year edition and it says my Video drivers appear to be out of date. Which it says they are, Windows XP, VisionTek XTASY 9550, Version . So should I, and how would I update this. (Also, question for anyone who has Half-Life 2, does yours requires steam to play? My copy plays through steam only it seems).
And Question 2 is, my sound card is old, and the power supply I bought doesn’t have a cord that would fit my version of the sound card. Can you actaully buy a piece to convert it to the right plug style (Can’t remember the name for this piece of hardware even though its sooo common, but I am tired, so gimme a break)?
I thought I also had more questions, but at this point I can’t remember. I need a bit more sleep, and I will post them later if I can remember any.