Me too... been there, done that. With my last EC, I had to cut holes in the back for the 27" CRT, and the receiver. Because of the weight of the receiver (about 40 lbs) I was only comfortable putting it on the bottom shelf, but because of its width, to get the thing in there you had to take out the shelf above, carefully navigate over the door hinge (yes, it was that tight), and carefully slide the beast down to the bottom. Some fun. And connecting stuff to the back? What a pain. Short of further butchering to the back panel, you had about a 5 inch high, 10 inch wide opening to work with to make receiver connections.
Currently I'm using towers similar to these
, from the same local company. I bought mine about four years ago, so the exact models aren't on the site anymore. They're about 20" deep (24" would have been ideal), and 24" wide. The opening on the back is large and spans the top shelf and a portion of the next one down. You can position the remaining shelf in such a way that you can run cables down the back between the shelf and the back panel. I don't know where you are, but if you're really unhappy with what you've got, consider purchasing from them. No, I don't work there or know anyone who does.
Mine cost me about $250 CDN each (x 2). Well made, flat pack, build it yourself. Glass doors, heavy MDF. Considering other furniture choices, they were cheap, easy to assemble, and they do what I want and need. What more could you ask? OK, maybe three or four more inches deeper. LOL.