NEVER!!
Personally, I find Mac OS X better to use than Windows XP. And the only time my computer will crash is when I drop it.
As seen on CNN last night, I quote Steve Jobs;
"The Intel Dual Core will run 2 to 3 times faster than the G5."
"The iMac will come with all the same features, iSight, the remote, Mac OS X all with the same price."
The new notebook from Apple is called MacBook. Personally, I think it is a very lame name.
*plans to drop his powerbook more often, "accidentally"* hmm....