Solux makes MR-16 12V bulbs, and now also 120V bulbs (1.25" thread it seems).
If the reflector of your lamp is white (ie spectrally neutral) enough, that may be the simplest solution for good lighting.
Or if you can find them, tungsten daylight bulbs are difficult to find (quite impossible here in EU) but not that bad if they are around 5000K (beware that 6500K is a bit too blue for most tastes, may be due to Mr. Kruithof's curve?).
As a last-resort, mixing fluorescent daylight bulbs (too blue, too green, too spiky) to standard tungsten/halogen light isn't that worse.