You'd be surprised how much improvement switching over to a Solid State Drive will make. And faster USB ports help a LOT if you have any data hungry peripherals like disk drives as well. I've always believed in buying as much speed as is available to make the machine viable as long as possible. There always seems to be a new killer app or capability that comes along and makes even the fastest obsolete, but it may take 5 or 6 years.
FWIW, this new MacBook Pro uses a four core i7 and it's been kernel panicking after a long string of DVD file format conversions. I haven't been keeping an eye on CPU temperature, but I think I'll take a look next time to see if that might be the problem. Wouldn't surprise me, as laptops aren't known for having good cooling systems.
Good luck in your search for a replacement rig.:thumbsup: