Can I cut through a section of marble worktop with a normal hole saw?

Or what other tool would be better....

I need to make holes for pipes etc

You'll need diamond dust hole saws. Can't think of another way.

Water jet

Diamonds or waterjet .....or a shaped charge!

Try

http://365drills.com/

Much cheeper than the other options.
Depends how thick the marble is but you should get through with just one hole saw

Kev

When I've seen people using a hole-saw in stone (inc. marble) they were using a water spray to help to cool the saw - just a hand-pump spray, like you'd use on plants.

I'd guess that it also keeps the marble cold (to prevent overheating and cracking) as well as keeping the dust down.

Bet it makes a mess, though...

UPDATE: those 365 drills don't seem to need water.

[Edited on 20/6/09 by David Jenkins]