I have a layout I'm testing that some people have said is looking blurry in Vista.
Can someone check this link http://ilmigliore.com.au/staging/
And let me know where they think its gone wrong?
Nothing is blurry and Vista does not make anything blurry. Your user probably has their screen set to a lower resolution than their monitor's physical resolution. That would blur all text, not just webpages.
If you want to see for yourself, download Microsoft Virtual PC and a Vista virtual drive image. Both are free from Microsoft.
Vista also uses Vista fonts by default (Calibri, Cambria, Constantia, Segoe UI, etc), and while some of them are wonderful fonts IMO, they all require ClearType to be enabled, otherwise they look awful. It's possible, though highly unlikely, that the person with the problem has Vista, has his system set to override your font stylings with the system defaults, and has disabled ClearType....
Okay, it's not very likely. Dan's explanation is better.
What would you say to a client who is insisting that the layout in the OP is blurry and that other webpages are fine?