Marketa,

All though playing with the computer is a good way to learn parts.... It is not the same as playing with real live people. It can be useful but it is not the same as having riffs pop up unexpectedly in a jam, or nailing a complex harmony part, or finally playing a finished piece of music together.

I practice to jam tracks... but I enter the magical relm of performance when I play with other people. Most of those people are good friends and adding this to our realationship really made both the music and the friendships better.

So I would submit that there is benifit to playing with jam tracks or recordings, but... Practice with the computer, but don't give up on finding people to jam with. Keep looking!! Music is supposed to be LIVE. The contrast between the two, is like the diffrence between masterbation and sex.