Sonic the Hedgehog turns 21 this week and whilst he’s off down the discotheque with Tails (presumably) Microsoft are celebrating with a dedicated Deal of the Week sale on a few select XBLA games:

Sonic 4 Episode 1 – was 800 MSP, now 400 MSP
Sonic Adventure – was 800 MSP, now 400 MSP
Sonic Adventure DX Upgrade – was 400 MSP, now 200 MSP
Sonic CD – was 400 MSP, now 200 MSP

There are also a few avatar items in the sale which you can check out here. These prices are valid for Gold Members only and will be valid from today until June 25.