Software

Windows uses a swap file system method and if there is not enough space then it can slow the system down. If i were you i would save everything on another hdd (external) and give the internal hdd a good format, load on windows and then transfer the files back over.

The 15% is the amount of total free space that should be available on the hard drive.

Not just 15% of the hard drive but 15% free space that is contiguous (all joined together as one block of space).

Windows uses more than just the Pagefile in its runtime environment, many M$ applications make use of Temp directories and files that the user never sees because the files/directories are deleted at system shutdown. However, if the free space is not contiguous, the Temp files may end up fragmented as soon as they are created, thereby causing system slowdown.

This aspect of the PCs operating system is all but transparent and very difficult to diagnose other than to check for contiguous free space. One help is to disable then delete the Pagefile before running the defragmenting program. IThis way you immediately generate a chunk of unallocated hard drive space that can be better utilised by the defragmentation process.

After defragmenting, re-create the Pagefile and reboot. Better to define the Pagefile as a set size of 1.5 times total system RAM, rather than a 'system managed' expandable Pagefile (which tends to lead to Pagefile fragmentation).

If opening a file can take up to 3 minutes, check to see what is grabbing all the clock cycles during that period of time. Something is clearly using the processor in the background.

Another resource-hog can be the number of screensavers a user has installed within System32, as they are all partial loads for easy startup when required - I don't use screensavers at all therefore deleted them all.

A nice purty picture on the Desktop is also a resource-hog so DUMP IT, opting for a plain monochrome colour of whatever the users choice may be - the system is there for working on, not for sitting gazing admiringly at.

You could also slim down the bells and whistles on users' Desktops, favouring to run with the setting for 'Maximum Performance'.

Unless it is a laptop frequently used for presentations you can also get rid of the Hibernation file, thereby freeing up more space for the Pagefile, Temp file, contiguous hard drive area.

If I think of anything else I'll add it later. :)

Gents,
thanks for the quick responses and excellent suggestions, i am going to try and remove and rebuild the PF, ill keep you posted.
thanks again.
MF