Well, if I were you and had 1-1.5k to spend on a new set up I would purchase the following:
1 LDC = Oktava MK 219 modded by Mr Joly - 300 dollars (in the classifieds section right now)
M-audio Profire 2626 8 channel interface with pres - 600 dollars
Which leaves 600 dollars for monitors
But honestly...you will deff benefit from treating your room before upgrading your monitors.
I recently made nine 4' x 2' x 4" rockwool pannels for around 300 dollars.
Use the other 300 for the monitors, unless you want to sell a few of the things you won't use anymore like the bx5's and then look out for a nice pair of monitors. As I think of trying to suggest monitor pairs though, I'm really confused... Event ASP8's are pretty good, Yamaha HS80m's are too, and Mackie hr824s can handle their own pretty well. All can be had slightly used for around 400 dollars.
Best of luck.