The specs you have drawn up are more than adequate for the purposes you have described the only thing I would add is another hard drive and have them set up in a Raid array ..... a mirroring setup will slow their operation but reduces the likeliehood of data loss through hard drive failure. Your external drives are then an additional safeguard.
I always trust your judgement
Confusing me with someone else again
However, my experience of 'local' purchases by friends is that they seem to go wrong far more than my Dells.
Given the quantity of machines produced by Dell the percentage that goes wrong is extremely small but there are customers out there who swear at their Dell machines rather than swear by them. However you can always find vociferous unhappy customers of any manufacturer whether a multi national company or the corner shop.... My own bugbear was Compaq - I liked the machines but found the company diabolical to deal with when a fault arose.
So a top of the range graphics card would be my best bet?
Not a top of the range card but one just a step down from them would be fine for your purposes and one with plenty of onboard memory of its own.
