My new iMac is great, apart from one thing, the mighty mouse feels sluggish, double clicking and tracking just feels, well not smooth. I first thought this might be because ive only got 512mb ram, so ive stuck another 1gb in, which i was going to do anyway, and brought home my wireless MX700 mouse from work which works smooth as butter on my machine at work, but its the same. Its maybe slightly better than the mighty mouse, but i had heard people raving about it, is the mighty mouse actually just a poor mouse? Could anyone recommend a nice smooth mouse - as this is annoying me so much im considering returning the mac as a result, in every other respect i love it, but the mouse problem is really taking the shine off it. Btw: ive tried both with and without mouse mats. One last thing - do i need to defragment my hard drive, if so, how often and how do i go about it?