The Compaq Presario SR5010NX http://h10010.www1.hp.com/wwpc/ca/en/ho/WF06b/12132708-12133156-78308260-78308260-78308260-79685091-80159593.html seems to have a Celeron D 360, which is an LGA775 socket 3.46GHz cpu running on a 533 Front Side Bus.  It also has 512K cache, which makes it pretty fast and almost as fast as a regular Pentium4 running at the same clock speed.   Since the motherboard supports E4x00 Core2 Duo cpus, that would be the best improvement - an E4600 2.4GHz is significantly faster than a Celeron D.

So could you give me a suggestion what CPU I would need? See this link. The reason I want to upgrade is that I want to convert VHS to DVD.
http://shop2.frys.com/product/5126086?site=sr:SEARCH:MAIN_RSLT_PG

Requirements

Processor: Pentium IV 2.0 GHz or equivalent

I would go for the E4600 or E4400 - they might be a little hard to find, as they have been superceded by the newer 45nm cpus (which won't work on that motherboard).  

Have you tried the software? The original processors (Celeron D 360 and Celeron 356) should be enough for that software, they are better than the old Pentium IV 2GHz.

I am afraid to try it. If it does not work then I can't return it.

The only thing that would happen is you find the video compression takes a long time.  Regardless of which processor you use, it will work; the only question is how long it takes.  The recommended processor is not a hard and fast rule when it comes to video compression, and a Celeron D 360 will work.

Believe it or not they were converting VHS to DVD way back in the '90's before 1.0GHz P3 were released.