Not enough memory to complete this operation

Hi, I get this message when manipulating very large images that have been scanned in. Under processes in Windows Task Manager, the memory usage for PSP8 is 1.38 Gb, ok that is a lot, but there is 3Gb of memory on the machine, (all of which is being recognised by Windows), there is also 5Gb of virtual memory reserved. Just wondering if there was some restriction in PSP8 that I could turn off, or am I missing something about how much memory is being used in total? Is there a way to get Windows Task Manager to show total memory usage as a side issue?

Technical details: I am using PSP8.10, under, Windows XP SP2, I have 3Gb Ram installed, made up of 2x512, 2x1024, a dual core AMD64 processor.

Would really appreciate any ideas if anyone has overcome similar problems.
Many thanks,
Rob.

just came across this function:

Paint Shop Pro Build Information:
Build Date 03 December 2003 @ 16:47:54
Build Mode Release (8010004)

Hardware Configuration:
Processors 2
Processor Type 586
MMX Support Yes

Memory / Drive Status:
Memory Load Index 63 pcnt.
Total Physical Memory 2.00 GB
Available Physical Memory 1.08 GB
Total Paging Memory 4.00 GB
Available Paging Memory 4.00 GB
Total Managed Memory 1.24 GB
Total Handles: 173
Temp Drive Free Space 21.68 GB

Video Driver Information:
Bits Per Pixel 16
Number of Colours 65536
DIB Output 24 BPP
Palette Size Non-Paletted
Resolution 1680 x 1050

Operating System Information:
Operating System Windows XP Service Pack 2


which you can get at through Help->About->System Info.

Total Physical Memory 2.00 GB
Available Physical Memory 1.08 GB

is what I don't understand, why is it only seeing 2GB, is there a way to set this?

If your version of WinXP is 32-bit (not 64-bit), then it will only use up to 2GB of memory for any one application.

Thanks very much. I did a bit more reading about this and came across a very good article that looked into this in depth, here: anandtech.com/gadgets/showdoc.aspx?i=3034
just in case anyone else is interested in learning more about it.