Hi. As the person above noted, if you have software version 4.0 or higher you can go to Options--> Security and select Wipe Handheld. Alternately, if you do not have that option you can go to Options--> Security and enable a password and enter it incorrectly 10 times and that will wipe the handheld. However, be warned I am a tech support agent for Nextel Blackberrys and I have seen far too often that doing it this way can cause real problems. After wiping this way the phone automatically reboots itself and sometimes the phone will never boot back up, instead it will just sit there with the spinning hourglass and you would be lucky if you could get Desktop Manager to detect the Blackberry in order to reinstall Handheld Software. Just so ya know!
You should be fine. I am NEXTEL (now Sprint/Nextel) support but I do know that the only thing required is the 4.0 software. You will know if you are able to Wipre Handheld or not because when you go into Security and click the trackwheel either you will or you will NOT have the option. That is the only way to know for sure.