A new month, a System Update, and another list of Xbox LIVE Marketplace dates to note down. As always, this info is from Major Nelson, LIVE's spokesperson-in-chief.

Xbox LIVE Deal of the Week:
April 12: Left 4 Dead Crash Course, 320 Points.
April 12: The Maw, 400 Points.
April 19: Borderlands Zombie Island, 400 Points.
 
Xbox LIVE Games on Demand:
April 13: Devil May Cry 4 (Europe, Australia and New Zealand)
April 20: Halo 3 (All Xbox LIVE Regions)
April 20: Saints Row (Europe)
 
Xbox LIVE Arcade:
April 14: Final Fight: Double Impact, 800 Points.
 
Xbox Avatar Marketplace:
These are just a few of the collections scheduled for the Xbox LIVE Avatar Marketplace.
April 13: Tom Clancy's Splinter Cell Conviction.
April 15: Forza Motorsport 3.
 
Xbox 360 Game Add-Ons scheduled to be available:
April 7  Mega Man 10 Bass and Mega Man 10 Special Stage 1 Game Add-ons, 80 points each.
April 13: Forza Motorsport® 3 Road & Track Car Pack, 400 Points.

Be aware that this is posted from Xbox US headquarters, so things may be region specific.