Over $1 billion was spent on desktop computers in the US on Thanksgiving Day 2014

"comScore (NASDAQ : SCOR), a leader in measuring the digital world, today reported U.S. desktop retail e-commerce spending for the first 28 days of the November–December 2014 holiday season. For the holiday season-to-date, $22.7 billion has been spent online, marking a 15-percent increase versus the corresponding days last year.
Thanksgiving Day saw a significant 32 percent gain to $1.01 billion in spending to surpass the billion dollar threshold for the first time in its history and marking the first day of the 2014 season to reach that level. Black Friday (November 28) followed with an even stronger spending day with $1.51 billion in desktop online sales, up 26-percent from Black Friday 2013."
Source:  Press release from comScore, 30th November 2014

Note - some reports put mobile spending even greater than desktop