What format are the recordings now? I thought Media Center recorded in dvr-ms format, which would not be compatible with dvd players. Or am I misinformed on this point?
It is possible to to take them out of this format and simply have the mpeg2 files, or convert them to a complete dvd ready to burn.
In any case, you should try a free burning program called ImgBurn. Use good media like Verbatim 16x disks, and burn them at either 8x or 12x speed.