I'm sure many are aware that Vista will be shipping 1st Quarter 2007 for retail. It should ship to Businesses November.
However i heard on the TWIT podcast that Dell will be giving vouchers towards the end of the month with their new PCs so you can upgrade for free ( probably the higher end PCs).
It seems like a good idea to hold off a new PC purchase over the next 2-3 weeks until retailers give the Vista Voucher. this could save several hundred pounds. However if you want XP and don't care for a new OS don't worry.
May be worth mentioning this in the Thursday Dell deals?