Tough situation with low-light indoor photography and cameras?

I'm having a very difficult time with deciding if -- and how -- to use a Canon DSLR -- an EOS-1D Mark II -- that I received a while back.

Here's my problem. In a few weeks, I'm supposed to shoot a meeting that will be in a room that's not very brightly lit. The subjects will be stationary, which is good. But anyway, in a low-light room, a low ISO obviously won't do. But a higher ISO will mean more sensor "noise", which is what I want to avoid.

The EOS-1D Mark II is old but good quality, I'm told… But it has no built-in flash. I know it has a "hot shoe" for mounting a flash unit, but I've not used one of those before, so I don't know whether there'd be a steep learning-curve.

Alternatively, I can use another DSLR I own, a Nikon D40X, which DOES have a built-in flash… Though I'm told the image detail is not as good as the Mark II.

So what can or should I do? If I want to use the Canon, do I pretty much need a flash unit to make up for the low indoor light? Or is there something I can do with the settings (ISO, etc) that would make buying a flash unnecessary?

Or would I be better off just "biting the bullet" a little (with image quality) and use the Nikon that already has the built-in flash?

Any thoughts very much appreciated. I'm sure this sounds a "duh" question to a lot of folks, but I've got some long-term memory problems (due to a medical condition), so it seems like I can't remember much of what I learned back when I took photography courses.

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