Nerd Alert! Computer Upgrade Advice needed!

[Moogled]

Currently running a Pentium 4 3.2ghz with 1 gig of RAM. Using ATI Radeon X1650 Pro.

I'm looking into upgrading my system by the end of this year and I've been reading into Dual-Core systems, multi-threading, and processor/motherboard compatibilities. At this moment, multi-threading seems to be beneficial only when applications support it.

I use my desktop as a media device; playing games, listening to music, watching movies but I would also like to burn DVDs.

What are some suggestions/advice as to if I would be reaping the full benefits of a dual-core system rather than just upgrading to a much higher single cpu?