power surge | loud noise | no boot | mobo issue?

hi all. i just built my first computer in july, and yesterday all went bad!

in advance, please tell me if this is the wrong section, as i am guessing as to what the problem is. could be a power supply??

here's what i have:
BIOSTAR AMD M-ATX M7NCG400 RTL - microATX mobo for amd
CPU AMD|2500/333 ATHLON XP BARTON
DDRAM 256M|DDR333 PC-2700 - 2 sticks, so 512M RAM
WIN XP HOME
A-Power 320 Watt mATX power supply

was working ok until a couple of days ago. i was playing a game and the puter froze and made a loud noise (through the headphones). i thought nothing of it so restarted. it was also periodically telling me the internet cable was unplugged when it was not.

then yesterday we either had a power dip, a power surge, or my computer fried and stole the electricity from everything else. the tv went out for a sec, the cable box rebooted, and the computer crashed and never came back. Oddly, I had been playing with the pc settings in the front, so I happen to know the temp in the box read 35 degrees Celsius... if it matters. I was running a microsoft game, probably an email app in the back, and maybe a browser in the back as well.

so here are my questions:

1. is it a mobo fry? how can i tell?
2. is there something that i forgot when i built this thing? is there a ground i should have used? the mobo is connected to the case through the screws, but other than that i don't know of any grounding in there.
3. is there anyone who can help me figure out what to do? could it be a power supply problem? is the power supply too large or small for this?

should i just buy a new mobo and see if it works? is it possible it is a ram issue or that everything is fried?

as you can see, i know very little about this, but want to fix it!

thanks!