System Requirements are found here, at the bottom of page:
http://www.telltalegames.com/store/talesofmonkeyisland
and they are:
System Requirements:
Operating system: Windows XP / Vista
Processor: 2.0 GHz + (3 GHz Pentium 4 or equivalent rec.)
Memory: 512MB (1GB rec.) Sound: DirectX 8.1 sound device
Video: 64MB DirectX 8.1-compliant video card (128MB rec.)
DirectX®: Version 9.0c or better