I started down the road you did about 12 months ago and have now got my satellite motorised and a tried a few different boxes before settling on building my own HTPC (although haven't quite got the server bit figured out), so it can be done, but does take allot of reading and fiddling about.
The general advice I would give is look at it as a hobby with a 'goal' of having a nicely set up AV system, rather than wanting to have a direct replacement for your current sub. I think that those that set out to 'have more channels' or 'watch more games' tend to be happier than those want to keep or gain specific channels or follow a particular team or sport.
Regarding a box, I would say that you already probably have one of the best boxes for a newbie, otherwise maybe try a non-linux Technomate box. Otherwise try a Dreambox or a VU; at least you will be able to easily sell them if you don't get on with them.
The general feedback that I got when I was starting out was go for good quality (is doesn't necessarily mean the highest price) and had numerous recommendations for T&K brackets, Webber cable, Inverto LNB and Technomate motor.
Good luck!
bb69