I bought an HP S3430F Slimline HTPC and I've been setting it up today. Comes with the LG Blu-Ray / HD DVD combo drive, 4 GB RAM, AMD Quad processor, wireless internet, remote control, TV card etc.  It is a powerful little box, one-third the size of a desktop PC, so it fits nicely in my A/V credenza. I also bought a long range wireless keyboard and mouse so I can use the PC from up to 30 feet away. Connects to my Onkyo TX-SR805 via HDMI.

Bought it mostly for Blu Ray movies and it works well for that. What I hadn't thought about so much was playing music through it, but I've been ripping CD's in lossless format with excellent results using  Windows Media Player.  Ripping now as I write this post using my plasma TV for a monitor.

Given the price of Blu-Ray players and a music system like Sonus, this seems to me to be a great alternative.  Has the added benefit of full PC usage as well.

Still experimenting with it but so far this HTPC seems like a great way to go.

Mike