If anyone is interested, apparently there is a deal to be had at the moment... if you buy VMWare Foundation edition before the 21st May, you will get a free upgrade to VSphere Standard after it's released (under the support and subscription contract). This is because there will be no more foundation edition under vsphere.
Get onto your reseller quick if you're interested...
I reckon it works out at about half price the price (so circa £3k instead of £6k+).