"PTVupgrade, a site that has been around for years selling pre-upgraded TiVo hard drive kits and upgrade services, has recently started work on a package for hacking DirecTV Series 2 TiVos, called PTVnet. The current Series 2 DirecTiVo hardware can run all the applications the standalone hardware can, but DirecTV never released the 4.0 OS to their customers. To let those users make the most of their crippled hardware, PTVnet will make upgrades and hacking easy by selling a pre-built hard drive ready to drop into a DirecTiVo box."I have provided a link to the PVRBlog site rather than the source article (on PTVUpgrade) because the former has a couple of other links that you guys might be interested in.