I had some really great information regarding this topic but I forget where I put it. Seriously though I made my first 5 batches using an aluminum pot but I cant remember what they were. 

   That myth you may have heard about Aluminum causing memory loss is bullshit, it may or may not affect the flavor of your brew. Even if it does some how change the flavor, I'll bet you wont even know after the first few.
I recently almost tipped out a 5 gallon batch "ala jamil" but I decided to let the beer sit for another week or so and things worked out for the better. 
I say that if the aluminum pot is all you have then brew on until you can upgrade to stainless.
Cheers,
HH