You can keep both MyDefrag and PuranDefrag installed at the same time. If you are going to use PuranDefrag, go to "Additional Operations" and untick everything (also, if you are using the schedule in PuranDefrag, make sure to untick all additional operations there as well). This is the way to make the two programs compatible with each other.

Oh, and just out of curiosity, what did you use to measure 10% performance improvement?

Can it be out of RAM issue? Photoshop can use a lot of RAM when rendering or saving stuff.

Btw. you should seriously consider upgrading to a newer OS. Win98 + Internet is not a good combination today.

I thought Win98 is very secure because nobody uses it, and therefore new viruses/malware will not run on Win98.

Well, if it is indeed a hard drive problem, then Spinrite may help (not free). Also, I would suggest checking his RAM with Memtest86+ to see there is a problem with RAM.
There are also various 'solutions' proposed on Adobe's forum:
http://forums.adobe.com/message/2700806.

I hope this will help.

1) Wrap around fragmentation wraps a file around an unmovable file in linear fashion. In terms of disk seeks, the difference between this and completely defragmented file is very small: even if file is not fragmented, hard disk heads still have to move when reading that file (so called 'track-to-track' seek).
2) Any file is rarely read in completely linear fashion. It's more like "Read first N KB of file A, then read J KB of file B, then return to reading file A, etc." In this case, it does not matter whether file A is slightly fragmented or not.
3) Wrap around fragmentation may also be beneficial, because free space is completely consolidated and given file does not have to be placed farther into the disk.

Pity there are only two defragmenters that use and understand wrap around fragmentation. These are MyDefrag and PerfectDisk.

Set it to Disable if you want to disable boot optimization, leave it at Manual if you want to have boot optimization.

It's "Disk Defragmenter" service.

Thanks for the tip! I will do it, but not until next week. Right now, I am busy with preparations for my final exams at university.

So the only way to disable or enable it is to disable or enable the service? This is good to know.

Yes.
But there seems to be another undocumented way to disable built-in boot optimization without disabling the service. Both PerfectDisk and Diskeeper are able to disable boot optimization without disabling service. I have no idea how they do it though.

The above registry key does not apply to Windows 7. Boot optimization will be performed regardless of this registry setting.

Isn't Intel X25 a better option in terms of performance? Or are you getting Hitachi because it's cheaper?

9GB partition? So are you actually running OEM version of Windows? Why don't you just delete this 9GB partition and resize next partition towards the beginning? GParted can do that.
Also, is your graphics card ATI or NVidia? If it is ATI, then you can safely disable "Catalyst Control Centre" using MSConfig. If it is NVidia, it is OK to disable all NVidia startup items except "NVcpldaemon" using MSConfig. This may speed up boot process by quite a bit.

P.S.: My hard drive is slower than yours: I get around ~37 MB/sec at the beginning (measured by HDTune).

Just measured my boot time, and it took 56 seconds to boot into Windows and start Firefox.
Specs:
Toshiba Qosmio F20
Pentium M @ 2GHz
2GB RAM
100GB 5400 RPM hard drive
Windows 7 Home Premium (32 bits)

Bloody, here are some explanation about services that can be disabled or set to manual start:
http://www.tweakhound.com/vista/tweakguide/page_8.htm.
Note: although the above link is generally quite trustworthy, it is still better to carefully think about disabling each service listed there.

Great idea. But what does it have to do with JkDefrag?

Oops, I put it here by mistake.

Thanks for sharing your idea, I appreciate it. Is the display a bottleneck on your computer? Not for me, but I can imagine that it can be on slow computers. I will put it on the wishlist.

Thank you.