thats the updater for the phone not the computer. so you will sync that program onto your phone and all your info on the phone will earase. but then when you sync your phone to your computer your hotsync will be updated onto your phone from the last time you sinced it.
easy way to do this is get on another computer and download your software fromt eh palm website so that computer has hotsync. download the sprint installer and update your phone. let the phone work then go to your computer and hot sync. all your info will be there again.
if you only have on computer go to the hotsync and go into properties (custom) make everything except your "intall" "do nothing" save teh do nothing as yoiur defualt to insure that it doesnt go back to "default" then sync your phone with the sprint updater. then go back into properties (custom) and switch everything except your installer to computer overrights handheld. then sync and all your info will be there.

the 650 doesnt come with a modem so you will need to search the web for the bootleg program to get your treo to work as a modem. if you have a 700 and above you just call your cell phone provider and they turn it on