Spyder3 + Dell U2410s in bright room

I'm doing basic sRGB work with Lightroom4 and have a Spyder3 to help me out. I've used this setup in a few different environments, but the past two have always been in dark rooms. In those cases, I was able to use everything at sRGB (the monitor, and all of the calibration defaults in Spyder3) and get excellent results.

Now however, I'm setup in a brightly lit room, all overhead IFL bulbs. I'm not sure what they're temperature is, but the room is bright.

When I do the ambient light test with the SPyder3, it always reports Moderately Low, even when I point the unit upwards. This is leading me to think it might be dying on me.

In any case, what would you recommend I set it up at - i.e. temperature, gamma, and cd/m.

Spyder3, using the Mod. Low ambient setting, recommends 5800k / 120cd/m, but I really don't trust it.

U2410 Monitors are setup at almost zero brightness, 50 Contrast, Standard color setting (rather than sRGB).

My goal here is color matching, so I feel that temperature is key.