Thanks guys. I appreciate the feedback.
While I really want to have the tank drilled, I also agree that it is a bit late in the game for that and besides being a huge hassle there is risk involved taking everything out of the tank and putting it back again.
I think I will have to go the overflow route, but I'm assuming that is a big step up from just running a canister filter/skimmer as I'm doing thus far. When I upgrade to a large tank someday it will without a doubt be a drilled one.
Uslanja, thanks for the recommendation on the Eshopps. I'll have a look at that.
I should be able to have this new sump installed within the next 2 weeks if all goes to plan. I really can't wait as it will also provide me with the space I need up top to get new T5's as well (either 4x39 or add 3 more 39's to the 3 I have, not sure yet).
Personally I would drill the tank. I have a 90g that I used an external overflow on it and found it to be a huge pain. If you ever have algae problems, you'll be cleaning that thing non stop. They are a huge pain to clean too.
I started without sump like you and decided to take the "easy" route by installing an external overflow when I added my sump. I regret that decision. So after a year I took everything out of the tank, moved everyone to some garbage cans while the work was done. It really wasn't that much work and I've been extremely happy with the drilled tank since then. I even took time to spray paint the back of the tank. It looks a million times better now.
Now I just need to fix my algae problem...