I think Borowski is at best a mediocre closer. He doesn't have a closers' repetoire, and you also have to remember that he basically came out of nowhere in 2002 to have a solid year as a reliever, and then became the closer in 2003 because the Cubs had no other real options.
I am also not sold on Hawkins having the head to be a successful closer. I can however see Farnsworth taking over for Borowski this season and becoming a dominant closer. Then again, Dusty Baker will probably just continue his idiotic practise of letting his starters pitch into the 9th inning, whether they've thrown 100, 120 or 150 pitches already, which limits the value of the Cubs closer signifigantly.