Scavenging old P4

Once upon a time, I purchased an IBM Netvista computer with a socket
423 P4 1.4ghz CPU. Then, just after the warranty expired, the
motherboard went belly up. By that time the socket 478 processors
were out, so I had the local shop scavenge the drives and build a new
computer for me. The old CPU and my 256MB of RDRAM have moldered
away since. IBM has a parts list here
http://www-1.ibm.com/support/docview.wss?rs=0&uid=psg1MIGR-4U8KVY&loc=en_US

Recently, I read about the Linux-based MythTV software, and thought I
might try and put the old P4 to use. Unfortunately, I've not built a
PC from the ground up before, so I could really use some advice, as I
have a number of (probably really dumb) questions.

I've bought a ECS P4VMM3 micro-ATX motherboard of Ebay. The board is
a socket 423 board, with 2 PCI slots and 1 AGP slot, plus onboard LAN,
Sound, VGA.

The new mobo says that it "accommodates 2 DDR (184 pin 2.5V) + 2 SDR
(168 pin 3.3v) DIMM sockets...." Does this mean that I cannot use my
old RDRAM in the new board?

Secondly, do I need to remove the heat sink and fan assembly from the
CPU before moving it to the new board? And, if I do, do I need to
look for a new heat sink, etc., for the new board.

Thirdly, I can't find anything in the new mobo manual to say if it has
a maximum size for the hard drives. It only says that the chipset
supports "ATA 100" drives. I'm looking at one (initially) 160gb drive
for the computer.

Fourthly, when I bid on the board, I didn't notice that it was
micro-ATX. Will a bigger case, like one for a standard ATX board have
the appropriate mounting holes, or do I need to stick with a smaller
micro-ATX type case.

Thanks, in advance, for your help.

Cheers,
Will
--
****
"If people don't know what you're doing,
They don't know what you're doing wrong."
--Sir Arnold Robinson, _Yes, Minister_