Device is full

Got knoppix 5.1 installed on a 750MB partiton of a 1 gig USB stick and a seperate 250MB partition on the stick for the knoppix image as per the normal stick install.
after doing "apt-get update" vast amounts of package information is downloaded and it chews up far too much memory on the approx 250MB of the knoppix.img file. so now when I do something I get "device is full". have trimmed down the storing of other stuff to a minimum but the package info is still too large.
1) what is the procedure to reduce all the package info already
downloaded and stored in the knoppix.img
2) Even if I try download say a knoppix.iso of 700MB to a completely seperate 1 gig USB, the temporary files from the download (bittorrent or straight download) are stored on the initial 250 MB knoppix.img partition and cause the "Device is full" message to abort the download. How do I get around this?