AAC is the short of Advanced Audio Coding which is an audio format co-developed by Fraunhofer IIS-A, Dolby and AT&T.  AAC format could only be supported by hard drive-based MP3 of Apple for the time being. The algorithms used by AAC is different from that by MP3, and AAC could provide a better sound quality under the condition of compressing files to 30 percents smaller than MP3. 

Zune is the name of both services that obtain and share the media content and a brand of Portable Media Player developed by Microsoft like iPod of Apple Inc

Xbox is a video game console competing intensely with the Nintendo GameCube/Wii or Sony's PlayStation/(PS2/PS3).Microsoft has published versions Xenon, Xbox 2, Xbox FS, Xbox Next, or NextBox, XBOX 360.

You may play aac (Low complexity) directly or convert aac to wmv first on PC.  Please install the aac decoder based on DirectShow on your Windows system. Run "regsvr32 CoreAAC.ax" to register the codec

Download Zune Xbox Converter to convert AAC to Zune/Xbox. Then use USB or networks to transfer the wma file. Or burn the files to CD/DVD, play disks on Xbox easily.

MP2 is short for MPEG-1 Audio Layer II. It is one of the 3 compression layers of MPEG-1 audio standard. Defined by ISO/IEC11172-3. mp2 was originally targeted at digital radio, TV broadcasting and the usage on Video CD. Though the standard was
finalized when MPEG Audio was further promoted to its Layer III (MP3) component, MP2 remains a dominant standard for audio broadcasting.

Windows bundles mp2 decoder, you may convert mp2 to wma directly, then play them on Zune / Xbox.