Does the numbers for ghz matter at all on a computer processor speed?

This computer I'm looking to buy has this computer with this kind of processor:

Intel® Core™ 2 E6420 Duo Processor(4MB L2 cache,2.13GHZ,1066FSB)

While the computer I have now is..

Intel Pentium 4, 2.4 Ghz

What's the difference?

And how is one better than the other..? I Know the question is out of line... but I'm confused on how processor speed works.

Of course the numbers for ghz matters...The larger the number the faster the machine is...

The above was true until Intel came out with Core 2 Duo...

If you switched from an older technology Intel Pentium 4, 2.4 Ghz to the newest Intel® Core™ 2 E6420 Duo Processor you'd feel like you died and went to heaven do to the increase in performance.

Dual-core processors, or more correctly multi-core processors (for you can have more than two) essentially integrate the 2 (or 4, or whatever) processors onto a single processor chip.

This allows programs to truly multi-task, but unless the OS or program is written to handle this correctly, you won't notice a performance improvement.

We currently have an issue at work where our RAD tool (PowerBuilder 10.5) does not support this new technology, and it appears that it will not do so for the immediate future. Therefore, customers purchasing machines with dual-core processors will not observe an improvement in performance if all they are using it for is PowerBuilder products. However, if the OS (and other concurrently programs) so, then there will be an improvement, even if it's only small.

There is a Wikipedia descripion of multi-core here.