Comparing motherboards and CPU's

Hey everyone, I'm deciding on components to buy to build a computer basically from scratch, but I have no idea how to compare different motherboards and cpus.

For the CPU, I was planning to get a Pentium IV D945 3.4 Ghz, which was listed under the subheading of Intel (775-DualCore)

but a friend recommended a Core 2 Due e6300 1.8 Ghz under the subheading Intel (775-Core2Duo), pointing out that it is $60 (Aus) cheaper, and saying that it would also be faster.

So my questions are.
Which out of those two is better?
Is it worth going for the slightly more expensive Core 2 Duo e6400 2.13 Ghz instead of the e6300?
Do I need to/should I match my motherboard to my CPU?

Thanks everyone