Well, having lived there for 9 years, I wouldn't really be concerned. Although, I may be half Egyptian, I'm considered as a complete foreigner, because of my Irish side.
Strange as it may sound, I'm personally concerned about going back there. I wouldn't define Egypt as a danger zone compared to its neigbouring countries. Its a much more serene place.
If there was one thing that I would warn you about, it would be prejudice. A lot of people there like to generalise, linking nationalities with governments (like an American could be talked to badly and disrespectfully, simply because of Bush's cock up, it may be similar with the British as well since our old friend Tony joined in on the party). That said, there is also the other, more pleasant side which is defined in Arabic as, in phonetic English, "Okdat el Aganeb" which literally translates as "Foreigner Complex". Basically, its exactly like Yellow Fever except with Europeans. I can tell you, if you meet any people like that, they'll most likely cling to you and want to be best friends.
Finally, in terms of transport, don't let them taxi drivers over charge you! I once knew a guy who spent 120 EGP on a journey which only costs 20-25 EGP (from Madinat Nasr (or Nasr City) to Medan Tahrir (Tahrir Square).