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two things, I also got a new copy of Half-Life 2, Game of the year edition and it says my Video drivers appear to be out of date.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 6.14.10.6530 . 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.