CS3 Ext. Vista 64 jerky mouse movement

Question

Hi there,
I have a huge problem with my 32 Bit Photoshop CS3 Extended under the operating system Windows Vista Business 64 Bit and don't know if this is a known problem or has to do with the 64 Bit or something. I don't know what to do more so I ask here in hope of some help.
The problem: When I use the f-key to switch to a mode where the image uses the whole space behind the tool paletts and use the space-key to switch temporarily to the move tool to move the image around, my next mouse movements with click actions will be really jerky.
To explain this further more imagine you are on a deep zoom level inside an image, using the polygon lasso to mark an object exactely, there's often the situation where you come to the border of what you can still see and what you can't see anymore. Here you'd use space and move the window a bit in the direction you want to continue marking the object. When I do that (in fact after the first time i do that) I see that the whole processing of generating those marking points with the lasso gets really jerky as if the pc is studdering. It is not possible to work fluently and/or fast this way. As you can see from my speccs (see further down for details) pc speed is no real issue here. Other things like GPU-heavy games (e.g. Crysis) don't show any studdering.
Things I already tried to no success:
1) deactivated version cue
2) bumped the memory that Photoshop may use from 2.5 GB to the maximum of about 3.5 GB. Windows still has plenty of memory left for itself as Photoshop seems to have a border here that windows itself hasn't.
3) deactivated GPU-Support temporarily
Some more information:
1) Windows and Photoshop are on their newest versions/patches.
2) There is no emulation software and no Nero installed.
3) The file I'm testing this with is newly made (ctrl-n) in a resolution of 1280x1024 @ 300 dpi plain white. This shouldn't be extremely large.
4) Computer speccs: Intel Core i7 920 @ 4000 MHz, 6GB DDR3-1600, Geforce GTX 285 Black Edition, Watercooling for processor and north-/south-bridge and condensators. The whole system resides on 2 500GB Samsung Spinpoint F1's that run in raid 0 mode for speed purposes. Partitioning is done so that the operating system, programs, data, temp-files, photoshop swap file, windows swap file (and some more partitions) are each on separate partitions.
5) CPU/GPU temperatures are on nice levels (about 50°C each) and at least what I see from the CPU usage all 4 CPU-cores are getting bored during all this (less than 10% usage each).
6) This is nothing that is limited to the polygon lasso tool: If i use the clone stamp tool or a brush I get the same problem after moving the image around with the move tool on a higher zoom level.
7) I didn't have this problem on my old pc with Athlon 64 4000+ single core with 2 MB RAM and Windows XP Prof. 32 Bit. Furthermore I haven't seen my new pc without that problem so far. So the problem exists from the beginning.
Any help is much appreciated! I hope I made myself as clear as possible. If there are questions on your side please ask.
Kind Regards
Steve

Answer 1

Yes, of course the guarantee is solely on the vendor's part. They give 5 years of guarantee on the hardware as they build them together.
That is an interesting information with CS3 and multi-core-systems. I shall google that and see what information I find about it. Thanks for the remark.
I'd be more than happy if some folks here could bring some more light in the 64Bit-RAM-size-scratch-disk-issue and how it affects CS3-behavior. Would be really helpful.
Right now it should be (almost) like this: Vista gets about 2.5GB of RAM, Photoshop gets about 3.5GB of RAM, that is if Photoshop would take it (I'm not sure if it does although I configured it to do so). Being able to use the whole 6GB of RAM was the reason to use a 64Bit OS.
EDIT: I found a test with dual-core and quad-core systems with Photoshop CS3. The operating system seems to be 32 Bit though. It seems that CS3 doesn't scale very well with 4 cores. It uses 2 apparently but cannot make use of more. But anyway as I said: My old PC with a speed of 2.4GHz (single core Athlon 64 4000+) whose clock-speed is not directely comparable to my i7's 4GHz because of efficiency did the job without studdering. It had only one core that was much (!) slower than any single core on my i7. Even if the multi-core cannot be used from CS3 one would think that it had to run faster with the i7. In my opinion it must have something to do with either the 64 Bit OS or the raid0. The partions were no issue on the old machine (although I used multiple HDDs in the past so Windows and Photoshop were on the same HDD on different partitions but the scratch disks were on another).