It might have more processing power that its predecessor, but Microsoft's Xbox 360 is taking longer to boot up, both in terms of consoles shipped and games sold. The figures below, from industry tracker NPD, show games sold in the US for the original Xbox in Q4 2001, and the Xbox 360 in Q5 2005 (each console's respective first Christmas).
XBOX
(Game: units sold)
Halo: 783,200
Project Gotham: 454,400
Dead or Alive 3: 402,700
NFL Fever 2002: 388,000
Madden NFL 2002: 307,000
TOTAL: 2,335, 300
XBOX: 360
Call of Duty 2: 509,400
Madden NFL '06: 298,300
Perfect Dark Zero: 290,500
Need for Speed: MW: 211,900
Project Gotham 3: 165,200
TOTAL: 1,475,300
On a related note, sales of the Xbox 360 itself have been slower than the original Xbox console. Manufacturing delays are most often cited as the culprit, but some point to the fact that there are few TVs out there - even in the US - that can handle a high definition (HD picture). On the opposite tack, some punters may be waiting for Sony's PlayStation3, which will ship with a high definition Blu-Ray DVD player (Xbox 360 has no HD player, though there are plans to possibly add an HD-DVD drive in future models).