A friend of mine got himself a new P4 HT by Hewlet Packard, supposedly has 2 procesors x 3.4GHz, (700eur), but it is kind of sluggish. He hasn`t opened it yet not to lose warranty, anybody knows what could be inside, how it works? He thinks he could speed it up by putting duo core intel, but isn`t sure if it`s worth it and if it fits (what kind of connector is in). Any ideas?

Hyperthreading technology in a 865 chipset family. Pentium 4 processors with speeds of 2.4, 2.6, and 2.8GHz. These new Pentium 4 "C" revision chips with Hyper-Threading technology and support for an 800MHz front-side bus, a bit slower by todays standard. They boosted clock-for-clock performance.

Very good deal for the price but no way they match the Core 2 Duo with much faster clock to clock speeds.
HT was Intel's implementation of SMT, or simultaneous multithreading, in which a single CPU presents itself to operating systems as multiple processors. Scheduling multiple threads at once allows the Pentium 4 to keep its relatively long 20-stage main execution pipeline full, increasing clock-for-clock performance.

Hyper-Threading does have its downsides, including some resource sharing issues.

For the skinny on the 800MHz front-side bus, you will want to read our review of the Pentium 4 3.0GHz and Intel 875 chipset. Those 865 chipsets Intel introduced big feature was an 800MHz bus... but that is now far from leading edge.
Those P4 "C" chips generally scaled better with clock speed, but not after Core 2 Duo came out. Just an older, but great technology but for the price, very good.

Thanks for the great info, now I see why the dealer shop played dumb when we went there and asked for detail specs:-)

1.Do anti spyware scans in safe mode.

2.Run CCleaner

3.Run the Defragmenter

4.Go into msconfig start up,and uncheck everything except Firewall/AV

If your into high end video games or video editing then Core Duo is better.

For everything else,what you have is plenty good enough.

It would not be a good idea to mess with system (maybe add memory).

Hp (and other manufacturers) ship their machine with so much "crapware" installed that they're almost guaranteed to be sluggish. Too many programs loading at start-up, nets too many processes running. Many of these pre-installed programs are too close to being "spyware" (at least for my taste), with pop-up warnings wanting you to upgrade to a retail version of a program which you don't actually need or use.
The free anti-spyware program "Spybot SD14" has a tool to do the same thing as running MSCONFIG but is more easily reversable and offers explanations of what the start-up programs/processes are actually doing.
Too many programs demand internet access to "search for updates" when they actually haven't been updated in months. Two choices here, prevent this in the program's preferences, or block them with your firewall.
My "Verizon Yahoo" browser seems to want to load processes that you don't need running until you use the browser.
Both Norton and Mcafee AV exert a considerable load on system resources "bloatware" as is called. The free AV programs "Avast" and "AVG Free" are better choices for protection.