Actually, I've installed my gig of RAM about a week ago now, and there's no doubt that has been a very significant performance increase. I'm really pleased with the effect that the RAM has had on OS X.
I had only briefly used Photoshop prior to my last comment on it's performance. Whilst I stick by what I said, I do feel that I prefer using Photoshop on my iMac. The general performance is much better, and because of OS X's multi-tasking I've been able to switch between things much more effectively. The bit where sometimes I feel my PC has an upper hand, is not always. Occasionally I'll feel that maybe when I'm sharpening, or resizing a very large image, that my PC always did it quicker. But it's odd, because when I do it again - it was instant, which my PC was not. It's all really confusing 🙂.
I get the feeling that somehow people think I'm trying to bash the Mac here and compliment the PC. Whilst I am/was a hardcore PC user, I'm loving my Mac, and wherever possible I use my Mac over my PC right now. It's just more enjoyable 🙂. Although sometimes I do feel a little cluttered with all these windows open.
As per reference to the mouse, I really don't know what it is, but I can tell quite a difference. It's not unusable by any means, but it just feels very strange to me. I'm pretty sure it's nothing to do with the mouse acceleration, as on my PC I always have mouse acceleration deactivated.