I will be getting a new PC late this year. The only demanding Application I use is Photoshop 7. I cannot afford to upgrade to CS which is probably coded for dual core. Suppose I get a dual core PC running at 2.4 GHz. Will PS 7 run slower than on my current 2.8 Ghz machine ?

The correct thing to call it is 'Dual core CPU'.

I don't know if PS 7 supports dual core CPUs, but anyway, I doubt if you will see much (if any) difference between a single and dual CPU running PS 7.

Software to support dual CPUs is still in the early (baby) stage of developement.

Sorry, I do not check for private messages

I bet you'd see a fairly noticeable difference with PS7...Any software that took advantage of hyperthreading (which has been around for quite a while) will take advantage of dual core CPUs. Adobe's software has always been geared towards high-end PCs, so I would be surprised if they weren't doing quite a bit of threading. There's a huge difference between single and dual core in premiere 6.5, which came out around the same time.

One thing that I see omitted from dual core discussions in this forum is the fact that no matter whether or not the software takes advantage of dual cores, the operating system always will. Windows is constantly taking up CPU time, sending messages to each open process, checking to see if any other processes need CPU time, etc. When all that can happen on one of your CPUs, it frees up the other to do the important stuff that you're really interested in.

Good luck,
-SN