genebort-
I trade from home for a pro firm. What you miss is the interaction with the other traders. This includes someone noticing a stock that starts to move, a sudden gapper, maybe some advice on how you blew that last trade or just general chit-chat. These are very important things and must be weighed carefully when you remove yourself from that environment. I voice chat online with a few other traders before the market opens and during the opening (one trades at home and the others are in offices). I also am on mIRC chatting with friends throughout the day. This helps me to have a little perspective on what's happening in the real world and avoids, to some degree, what people call "hermit" trading.
For me, I LOVE working from home, but it does take it's toll on my marriage. It's much more difficult to separate work time from "family" time (especially since I trade in an open room with no privacy.
As far as the physical equipment... my suggestion is that you have redundancy at EVERY LEVEL POSSIBLE! I have 2 DSL lines (and a cable modem now because I'm afraid one of my DSL companies will go belly up any day). I have numerous computers running in redundancy in critical areas. All equipment is running off of UPSs (I live in California) including my phone system which is my last resort to get out of a position. Just one failure at any point could easily cost more than all the equipment you'd have to buy.
One other thing, and I guess this depends on where you trade, I still have to pay "rent" to my broker and I have to buy my own quotes.
The upside is I can wake up at 5:20 and start doing research at 5:21. If I get tired of trading I just go upstairs and go back to bed.
It's a wonderful life!
Fletch