ACPI = Advance Configuration Power Interface
it basically allows your computer to control the power functions of the system (e.g. turning off the computer when you shut down, or turning off harddrives to conserve power on a laptop, etc)
some more advice, here (if you choose to go with Fedora Core 3 - which is what i'm running)
When you're installing, if you have problems loading the installer (it will ask to verify the install disks [media], and afterwards, it will kick you out of the setup, saying that the setup terminated unexpectedly)
if you're using a DVD drive to install the OS, then try @ the initial screen boot: linux ide=nodma acpi=off i8042.nomux
That's what got me through the FC3 installation on my machine (XP 2500+, R9600 pro, 512MB DDR, Lite-on CDRW, DVD-drive, USB mouse, USB keyboard)
another thing to note: FC3 MAY NOT RECOGNIZE a USB keyboard during install... you'll have to use yum to update your HAL and HOTPLUG rpms.
As far as distro's for a newbie (n00b to n00b) - I'd suggest either Mandrake 10, or Fedora 3... I've tried also Debian, but it's lengthy and a P.I.T.A. to setup, but it's supposedly easy - but I spent 6 hours going through package selection, installed it, to not have it work.
Mandrake worked well for me, but it didn't challenge me enough - it's great for Hardware compatability (almost similar to windows)... Fedora 3 is good if you like a little bit of a challenge, and a little bit of a pain in the butt... Once I got my USB keyboard working for it, I was flying :P
Anyways... good luck in making that decision - and as for you joining us linux-typez0rs.... ~kudos~ to you!
- I M A