ASUS A8N5X Motherboard

I used this for my first custom built PC and I can't recommend it enough. Its got a great price and great features.

Its easy to install and everything fits in perfectly. Its easy to tell where things go and has lots of slots to put stuff. Theres 1 PCI-Express X16 slot, 1 PCI X4 slot, 2 PCI X1 slots, 3 PCI slots, 4 SATA slots, 4 slots for your RAM (4 GB Max), and tons more. The integrated sound offers 8 channels and has 4 USB ports for the back and up to 6 more.

The included instructions are detailed and help out first-timers like me :). The software is great and includes overclocking software, preformance details, an nVidia firewall, "Cool and Quiet" software, and even a screen saver with some others. Another one is the sound station which is fun to play around with.