There's no need to change your OS (especially because the OS really doesn't matter anymore). If you're tired of the beachball, get a RAM upgrade. I can upgrade my machine (which has 8 GB) to 16 GB for about a day's pay (or two). And I don't make very much money right now. Changing the OS usually takes an entire weekend (tweaking things and moving stuff takes longer than many of us think). So by the time you get it done, you've probably broken even.

Unless you like doing this sort of pain, in which case you can't be helped :)