Advice needed: AMD or Intel

Hi y'all. It's time for my trusty KT7A & 1.4ghz Athlon to hang up its
boots and I need some advice on my new system.

I've decided on either an AMD based 2800xp with Abit NFS-7 mb, or a more
expensive 2.8ghz P4 on an Abit AI7. Neither will be overclocked as I am
going for as quiet a system as possible so radical cooling is out of the
question. Is there any noise difference between the two systems with
stock heatsink/fans? The heavy duty activities the machine will be used
for are gaming and Mpeg 2 encoding (using Tmpgenc).

At first I was all set to take the AMD route without even considering
the P4, but then it occurred to me that mpeg encoding is basically a
pure number-crunching operation and that for this purpose the 2.1ghz
2800xp will be obviously inferior to the sheer power of a 2.8ghz P4.
Am I correct in thinking this, as I don't mind springing the extra bucks
for the P4 system if it gives me this 33% boost on my encodes?
Any advice appreciated.