Modding switch question

[mrhappy]

ok im new at this stuff so i have a few questions before i start adding maps to my Halo/Halo2:
-First if i switch all my original maps with new ones in Halo/2 with my modchip on then when i turn it off with the original maps be back again and so on so when i turn my modchip on they modded maps are there and then when its off it goes back?...
-Second i like playing Halo/2 on XB connect so i want to keep my original maps intact or it will screw up the whole system link process and i only want the modded maps for when i play with friends..is there a way to still keep my original maps and still have modded maps when i want them without switching them back and forth

I appreciate any advice you can give me for this problem...