iTunes question

okay, i have a question for all you savvier than i people out there.

i just came to the realization (yes, i'm slow) that i probably only have 1500 songs on my 40gb iPod and am up to 30gb because itunes has been defaulted to save my music files in AIFF format, and NOT in mp3 format. is there a way to convert all these AIFF files to mp3s without

a) erasing all of my formatting of the songs (i.e. volume adjustment)? i realize this is probably not going to happen, so i'm sort of resigned to it.
b) copying all 1500 songs and saving them 1 by 1 as mp3
c) do i really need a c) criterion? i just want to know if i can buy more room on the 'pod without it being a major thorn in my side.

help appreciated and accompanied by the joy that this brings.

(cherz rocks in the wacky seafood department. oddly, this came the morning after my own traumatic seafood night at red lobster with crazy mara and yaymee... i'm just glad it wasn't ME who got a faceful of lobster water)

update: thanks cherz for the input. it also turns out i'm oblivious to certain things, like when you right click on a song, one of the options is "convert to mp3" and i can do that and take up less room on the 'podster. doh! (i spent, seriously, an hour going through iTunes and iPod help menus and came up with nada. the answer was right in front of me the whole time.)

at least i have the end of quarter punchies to blame.