I guess I left some critical information out.
The PC does have some power as it is a dual core AMD processor. I have had it about 5 years. The iMAC is fairly new, about 8 months old.
I tried Parallels. Installed Windows XP in Parallels and did not have good luck with that combination. Baldur's Gate worked well. Shadows of Amn crashed the setup. So I dumped Parallels and switch to Bootcamp. Older iMACs would run Windows XP, but it is my understanding that now you can only use Windows 7 and 8 and it has to be the 64 bit version. I should have stated that I used Bootcamp with 64 bit Windows 7 Pro.
One other surprising thing happened. I forgot to run BiG World Cleanup.bat. I played the game for about 6 hours before I realized that. However, the game did not hesitate in the slightest. I ran BiG World Cleanup.bat this morning and it does not appear to make the game play any different or faster. Tonight I will defrag the hard disk, another thing I forgot to do. On my PC, I always need to run BiG World Cleanup.bat and defrag the hard drive to get the game play smoothly.
We have a Microsoft store in the mall near me. One of the tech quietly admitted that Windows works better in Bootcamp than on most PCs. The Microsoft techs still help you no matter what computer you have installed on Windows 7. More than I can say for the techs at the Apple store in that mall when it comes to help with the Apple programs.
I guess I could have purchased a gaming PC and got the same results. It is just that I really wanted to use Windows XP as the place where I work is committed to that version. Their custom software will not work on later versions. They found that out when they hired Microsoft to upgrade their software so it would work with later versions of Windows. So I bought the iMAC because an Apple salesperson promised I could install Parallels and Windows XP and it would definitely run all Windows XP programs. It runs most Windows XP programs but not the ones I needed.
But right now I am quite happy having both an iMAC and PC in one computer. The only drawback is that it is uncomfortable to switch from one to the other because it requires you to reboot the computer.
I was just sharing some information for those who may be in the market for a new computer. Something for them to think about. Before I bought the iMAC, I did buy a Dell. It came with Windows 7 Pro. But its performance left a lot to be desired. I sent it back to Dell.
Another thing to note is in Windows XP, it is much faster to use DOS than Windows for operations with large files and folders. When I load ~200 mods into one folder I can copy the folder faster with DOS than Windows. The same with packed files. I can unpack a large file much faster than I can copy the files in it.
Since I have no financial interest in either Microsoft or Apple, I do not care who buys whichever computer. I just wanted to share what I discovered. At least for me, there will be no more installing mega-mod games during the night while I sleep.
Hope this help someone,
Tom