Thanks Jan, and just wondering what you would consider "high volume"?

The sites I am looking at deploying are all essentially eCommerce sites, whereby the amount of traffic will be dictated by several factors, inc time of year (summer busier than winter ... just coming out of our summer though), school holidays and other unpredictable timings. So the traffic will not be consistent, however at it's peak we are looking at approx 1500 purchases in a day, at the very heaviest 1500 per day, per site (looking at 5 sites on one SQL instance, so 7500 purchases in a single day at the very, VERY highest. I'd be surprised to see that many in a single day though)

Its rather hard to tell, I have no sites running with express with that volume. The limitations in express is one cpu and 1gb memory and 4 gb Database size.

I asume if you get p to 7500 purchases the trafic is much larger so my recomendations is take the investment in a web edition.

But it would be nice to know if it worked with the express edition :)