I have Rev B. Though this site said it came with "Built-in AirPort Extreme", mine was an open-box from Best Buy and didn't come with the airport extreme. Another problem I've had is with the Built-in speaker, Headphone/audio line out - neither of these is loud at all. External speakers are a must for any kind of audio editing.
http://www.123macmini.com/specs/b.htmlApple Mac Mini 1.42GHz
Model: M9687LL/B
Processor: 1.42GHz PowerPC G4 (512K on-chip level 2 cache at full processor speed)
Memory: 512MB of PC2700 (333MHz) DDR SRAM, supports up to 1GB One slot
Graphics: ATI Radeon 9200 with 32MB of DDR SDRAM with AGP 4X support
Hard drive: 80GB Ultra ATA
Optical drive: Slot-loading Combo Drive (DVD-ROM/CD-RW), Superdrive build-to-order option
Ports: One FireWire 400 port, Two USB 2.0 ports, DVI output, VGA output (adapter included)
Networking: Built-in 10/100BASE-T Ethernet. (56K V.92 modem optional)
Wireless: Built-in AirPort Extreme and Internal Bluetooth
Audio: Built-in speaker, Headphone/audio line out (No Audio/Mic Line in)
Operating System: Mac OS X version 10.4 "Tiger"
Software: iLife 05, AppleWorks, Quicken 2005 for Mac, Nanosaur 2, Marble Blast Gold
Height: 2 inches (5.08 cm)
Width: 6.5 inches (16.51 cm)
Depth: 6.5 inches (16.51 cm)
Weight: 2.9 pounds (1.32 kg)