Mac? Use PwnageTool
Windows? Use Sn0wbreeze
Grab your 4.3.3 ipsw from here
Grab TinyUmbrella (Mac) (Windows)
Open TinyUmbrella, click advanced, and check "set hosts to Cydia on exit", close it, and restart iTunes.
Click simple mode in PwnageTool or Sn0wbreeze.
SYNC WITH ITUNES!!!
After it builds the .ipsw, put your iPhone in pwned DFU mode (SB does this for you, not sure about PwnageTool)
Then open iTunes, hold option (shift on windows) and click restore, select the custom ipsw (the one either SB or PwnageTool made for you)
It will already be jailbroken.