When I moved into my 1935 house four years ago I counted over 70 lamps of many different types. May of them were R63 and R50 spots and like you I was constantly changing bulbs - I keep a light bulb storage cupboard in the utility room!
I think that the spot type lamps are usually less reliable but you can buy extended life ones at considerable cost.
I've replaced 12 of my ceiling spots with 3 regular flourescent tubes and 4 under cupboard 12V halogens with 240V mini flourescents - I still have a light bulb problem because there's so many lamps but my flourescent tubes are cooler, cheaper to run and to date have never needed attention.
Throw the spots away and switch to flourescents where you can - the issue of lamps blowing will be nothing to do with the house or the wiring - just the lamps themselves.
This place in London sells lamps cheaply...
http://www.crselec.co.uk/
Good luck...
Peccavi
September 2009