I went by the Calrad booth at CES and it seemed that in order to get XLobby they want you to buy their HTPC and hardware.
I have to agree with Aaron There are a lot of very good programs currently availabe. I started with Media Portal and am also making the switch to XBMC.
There are MANY good competitors (XBMC, Media Portal, MCE Linux, MS MCE + plugins, MeediOS, Girder/NetRemote, Homeseer+Plugins, etc) now and the ones that have the most active communities (members, developers, plugins, skins, hardware support, etc)
The coolest new products that I saw at CES 2008 was Pinnacle Systems PCTV HD ultimate stick and the video transfer unit.
http://www.pinnaclesys.com/ces08/With the PCTV HD stick if you don't need to have an HTPC. You plug the stick into any computers USB port and you can watch and record TV to your hard drive or the internal 2 Gig flash memory built into the stick. This turns any computer or laptop into an HTPC with pvr capability. It also comes with an IR remote control which is about the size of a pack of gum, a dongle for pluging in external video souces and doing video capture and a RF antenna for TV and off air HD broadcast.
The video transfer unit allows you to send any video source to your video iPod or PSP with out having to have a PC or active sync.