"Safe" Fonts

According to http://typetester.maratz.com/ Trebuchet MS is a ‘safe’ font to use for web - is this true? do most pcs and macs have Trebuchet MS?

I agree with Arial, Verdana, Georgia, Times New Roman and Courier, but am curious as to wether i could (relatively) safely style text to Trebuchet MS?

I couldnt decide where to put this hope its ok :smiley: