Hardware and Vid editing

[Tempus]

Just double up your RAM and maybe invest in a fast HD. A Dual core @3.4 should be fine for video editing. If you really want to upgrade that's up to you. As far as your editing software?
First though, have you tried the usual steps; fresh install of OS followed by a reinstall of your drivers, codecs and software? If that gives you some improvement I'd just spring for the RAM.