If you actually play this game then you should know how the upgrades work. You find upgrade mods and pay for the upgrades. But to get easier upgrades all you need to do is go to a level that you beat and play it's minigames. They usually involve some kind of practice with either the wepon you gained that level or hacking.
Also you get upgrade points equal to the minigame level you are playing on for every rank E-B, but if you get to rank A you will get an upgrade for one of your weapons. An example would be if you played a level 3 game and got a C ranking for it you would get a total of 9 upgrade points. Three for each E,D,C.
But not all of the weapon upgrades can be gained this way, you may need to back track through levels to get more upgrade levels.
Also the best way to get rid of those pesky little bugs is to use the data launcer/sucker, not only do they die but you can use the stolen data to replentish your own heath!
Added by: Xrel Nov 22nd 2007, ID#1779