Microsoft has said that more than 20 million copies of Vista have been sold in its first month, more than doubling the initial pace of sales for its predecessor, Windows XP.

“We are encouraged to see such a positive consumer response to Windows Vista right out of the gate”, said Bill Veghte, corporate vice president of the Windows Business Group at Microsoft.

Windows Vista license sales after one month of availability have already exceeded the total of Windows XP license sales in the earlier product’s first two months of availability.

The more than 20 million copies shipped represent Windows Vista licenses sold to PC manufacturers, copies of upgrades and the full packaged product sold to retailers and upgrades ordered through the Windows Vista Express Upgrade program.