The quality of the picture is not determined by the firewire connection, as this is only used as a data connection between the XL1 and the PC.

The picture quality is determined by the speed of your PC, the playback software used, and the quality of the graphics card in it which is then connected to your HD TV via component, DVI or HDMI depening on the connections available.

The XL1 does not connect to the monitor directly. Think of it as a DVD rom drive with 200 slots, not as a DVD jukebox player like the DVP-CX995V.

If you already have your MCE PC connected to the HD TV, then that is the quality you will get regardless of the source of the DVD material (DVD rom drive, XL1, hard disk).