Whilst I agree completely with Tim, I would throw in a word of caution as I've seen this crop up before.
If you are upgrading from 3.2 to 4.3.3 that is a significant jump across a major OS upgrade and many minor versions in between.
In an ideal situation you will not run into problems, but if you do experience issues after the upgrade this will probably be down to incompatible settings being taken across from the very old 3.2 OS to the latest 4.3.3 one. Apple are good, but not perfect at getting upgrades to work.
If you are not worried about the application settings you have being kept, you could consider a "restore" rather than an "upgrade". This will set your iPad up as though it was a new device on 4.3.3. You can still sync all your Apps, Music, Video, etc back onto the "new" device, but you would not have your settings or saved data (e.g. game save information, documents, etc.) If this does not bother you, a restore may be a better route to take than an upgrade. When promtped at the end of the restore process, you would just choose "set up as new device".
If you do choose to go with the upgrade, that's not a problem. Just remember, if you do experience crashes, freezes, or just general instability, be sure to post back here and we'll see if we can help you resolve it. The answer will be to then try a "restore".
Hope that helps, and does not confuse you!