I hope this question doesn't get closed at once :)

I have an old laptop, a Compaq NC4200, which is going its final laps around the track these days. Battery is dead, and everything kinda runs slow. It also has only 1GB of memory, and even though I don't know if it can take more, I probably wouldn't be able to get hold of any that matches without having to special order it.

The size, however, has been ideal for my usage pattern, so I'm looking to replace it with a similarly sized laptop, at least in the same size category.

However, it's been a while since I tried keeping track of CPUs, so I have a question.

The old laptop has a Intel Pentium M 760 1.86GHz processor.

One laptop I found online has a Intel Pentium SU4100 1.3GHz dual-core. This type of processor seems to be quite common in the price and size-range I've been looking.

What kind of relative performance boost could I expect from the old one to the new one? I am not expecting a "about 7.45x speed", but some indication would be nice. For instance, dual-core tells me it might be akin to 2.6GHz, but I assume I can't simply compare 1.86GHz to 2.6GHz and expect the new one to run about 1.4x as fast, I expect more these days. Or is that unrealistic for this kind of processor? Do I need to up my price range and go for a 2+ GHz processor?