I have a failed Tascam FW-1804 (second time - needing factory repair). 
I now need to decide what, how and if I should go about re-setting up my studio.

I run XP on a very adequate CPU using Sonar Pro 5.2.  I need to have (min) 4 sets of analog audio ( left & right each ) along with 2 midi inputs (Motif ES and Tyros) to go to Sonar.  One analog output pair (monitor) is enough with the right interface.

My delimma is needing an interface that will meet these needs.  The 1804 did fine, and had all the inputs I needed.  Not that I want to purchase another, but I don’t even see it being offered anywhere for sale. 

One store said I could use 1 MIDI I/O and thru, and assign the send and receive on the keyboards and Sonar (respectively) to get the MIDI from both.  They were a bit unsure of how the settings would be laid out since they used different software & keyboards.  It is a fair bit of latin to me.

If it is possible to use 1 MIDI I/O for both then does anyone know the steps to go about this. I need both keyboards available.
There has to be a simple (permanent) way to accomplish this, with the wisest use of dollars.

I’ll buy what I need if it is prudent at this point.  I am wondering if the repair will run me as much as new equipment to re-set up the inputs/outputs.