IMAC G5/computer newbie/trashed a widget

hi ii have bought my very first computer all for myself. never had one before, i use'm at work , here and ther but not much.

My problem is i just bought a new IMAC g5 this month. Well i ooked everything up, etc.. but i started doing stupid things, probably cause it was so late and i was so excited yet tired. i accidently trashed my "widget" the calculator, and empited it! stupid, not a big thing right, well i cant get it back. I also moved some icons off the doc, with a little animated smoke and all!
I noticed in my applications there is now a missing space, where an icon was, now there is nothing.

i'm lame, i know. but can i just start from the very beginning like when i just openend it up and registered it, and i won;t mess with everything until i really know what i'm doing, i promise. Now, i dont have any files on the computer at all so i thought i could reinstall and start from the beginning i, have 2 disks that came with the computer, but i'm scared if i follow the directions and re-install the os system, that i will lose my ILIFE programs that came with the computer: idvd, garage band, , etc..

you see i don;t know if the ilife bundle is actually on the disks

at the end of it all, i'm typing this on a generic pc at work, i want to get home and fix this thing so , i can start working with my video and pictures, and sound, etc.. the whole reason i bought this imac in the first place.

but i need my calculator back...

Please help or direct me , thanks

david lost in detroit, mi