I thought apt-get was an alias of aptitude; either way, they use the same software sources and I've never had any problems using apt-get. Also, aptitude is definitely installed out-of-the-box in 9.04 and I'm pretty sure it's been there since I first used Ubuntu (6.06).
Also worth noting:
There is no need to download winrar to unrar UDB. Ubuntu comes with an "unrar" command. Again, I'm pretty sure this has been the case since 6.06.
Also, as has been mentioned, you should really use && rather than semi-colon, if putting things on the same line at all. I tend only to put things like "mkdir o && cd o" and "make && make install" on the same line.