First the VM thing.
On all the Mac OS's before X, there is a Memory Control Panel. Open it and make sure that the Virtual Memory box is checked. Then click on the Defaults button, if it is in the window. If the VM box is not checked, check it, click the Defaults button and restart your machine. By clicking on the defaults button, you ensure that the amount of VM available is the optimum for the amount of Physical Memory installed on the machine. Optimum is 1MB above the acutal. (512 actual = 513 VM) Unfortunately, OS's less than X did not have a wonderful memory allocation system and extra memory had to be allocated manually. To do that, do the following.
Find the actual application, PowerPoint. (NOT the file you are trying to open). Single click it, to highlight it, and then hold down the Apple key(next to the spacebar) and press the "I" key. Alternatively, once you have highlighted the application, you can go the the File Menu and choose "Get Info"
In the "Get Info" window, use the dropdown menu to find Memory. You will see three sets of numbers. Suggested Size, Minimum Size and Preferred Size. Suggested is what the writer thinks you should need, Minimum is the size, below which, the program will not launch and Preferred Size, the one we want, is the amount of memory that is actually allocated to the program. Try increasing this number by TEN THOUSAND (it's only 10MB) and closing the window. Try running the file again and see what happens.
You can increase this number all the way up to the amount of physical memory you have available, but that is not recommended.
Now, there is another possibility. If this is only one file, then it may be corrupted. How are you moving the files from the PC to the Mac?