Is Campagnolo 10 speed casset & chain fit with shimano tiagra 10 speed drive train?

For future reference, obviously, this is a "check before buying" sort of thing- the campag wheels are available with shimano/sram compatible hubs

Look for Ambrosio cassettes - You can get cassettes with campy spline and shimano spacing. I've done this the other way round for a campy gruppo on shimano wheels, works perfectly.

Check here:
http://www.ukbikestore.co.uk/product/387/ambr317/ambrosio-10-speed-casse...

Because i'm poor i've used the very much ill advised combination of 10 speed campagnolo gruppo with an old 7 speed shimano dura ace chainset and when the set up is right it works acceptably. It's not ideal but it just about does what it's supposed to, you can make almost any combination function if you are willing to take the time and set it up properly.

Give it ago, it will probably work, plenty of people have fitted a campag wheel to a shimano Gruppo in an emergency

All the above is true, but Shimano jockey wheels are more 'wobbly' so they are tolerant of the different cassette spacing.

Try it, it may well work.

The Vento, IIRC, has an odd lacing pattern that you can only use with Campag hubs, I am open to being corrected on this though, I'm not certain you can fit a shimano pattern freehub body on it.

As I say, try it, if it shifts well and isn't noisy, it's happy days.

That's probably your best option.

Where did you buy the wheels and Veloce stuff? If it's a LBS they may, with a little persuasion, swap them for equivalent Shimano bits. If it's an online shop like Wiggle you should be able to return them and re-order Shimano. This is your cheapest option.

Or, if you desire to become an initiate of the holy order of Campagnolo, you could junk all your Shimano bits and go the whole Italian hog. This will cost more but will ensure your eventual entry into heaven.

Shimano and Campagnolo 10 speed cassettes do not share the same spacing between cogs. Furthermore, Campagnolo 10 speed cassettes do not have uniform spacing between cogs across the cassette. So no, the combination of parts you chose is not recommended and will probably result in poor shifting accuracy and drivetrain noise, compared to using a Shimano cassette. It may work well enough to ride, but will probably require more frequent adjustment.