[Cheesus]

Ok, first off, what games do you intend to play, and how big a factor is the graphics quality? Second, do you have a particular screen size in mind? Multitasking going to be a big thing for you? Specific emulators you want to use?

After a quick google of your old notebook, that first one you mentioned is quite an upgrade. The biggest bottle neck you'll have is definitely the graphics card though...
In case you come across something yourself, if you intend to game, a dual core with a 8600GT or Radeon Mobility 2600Pro should be somewhere along the minimum.