Easier Way To Decipher Nested Nested IF's

I inherited a bunch of spread sheets which do some rather complex structural calculations. In trying to understand the equations I find myself using the VLISP editor in AutoCAD because it does such a swell job of syntax highlighting, etc..but it has its shortcomings when working with Excel equations. Yes, I know Excel will highlight matching parenthesis but these equations are to beat the band. Here's an example of one:

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I have also tried copying and pasting these equations into NotePad++ with again only limited success. I was hoping others out there might have some suggestions on any tools which can be used to easier trace the logic through complex Excel equations.

Essentially, this is what that formula is doing...
=IF(
...AND(H105=0,OR(I104=B100,I104=B102,I104=B105,I104=B108)),"BRACKET (RIGHT), PART #124",
...IF(
......AND(H105=0,OR(I104=B101,I104=B103,I104=B104,I104=B107,I104=B111,I104=B112,I104=B115)),"BRACKET (RIGHT), PART #125",
......IF(
.........AND(H105=0,OR(I104=B106,I104=B109,I104=B110,I104=B113,I104=B114,I104=B116)),"BRACKET (RIGHT), PART #126",
............IF(H105=2,"BRACKET (RIGHT), PART #53",
...............IF(H105=4,"BRACKET (RIGHT), PART #59",
..................IF(H105=6,"BRACKET (RIGHT), PART #61",0))))))

You will know better than I, what each of those parts is doing.

the formula editor Fx - Insert button to the left of the formula bar can be a HUGE help to breaking down a formula.
Then use ALT Enter and the different breaks, to make it easier to see wherer parts start and end (like I did above)