To backup your phone (nandroid backup) you'll need Droid2 bootstrap which is a paid app cost about $3 in the market. You also have to have it if you plan on Installing a custom rom. Im assuming your on gingerbread. You can use titanium backup to backup apps.
Make sure you get the X bootstrap. D2 Bootstrap is different and not compatible (I tried this once).
Titanium is also an awesome backup for your apps. I use it regularly.