How to upgrade my lighting situation?

Hi folks,

I currently own a Canon 7D and a 20D. Both get used.

Since I live in cold, wintery and dark for 6 months - Upstate NY, I do a fair amount of shooting indoors and end up needing to supplement lighting. I currently own a Speedlite 430EX, which has worked well for the last 6 years and can work as a wireless slave off the 7D.

I have acquired some good primes (35/1.4, 85/1.8) which will work in low light pretty well with the ISO bumped up on the 7D but not so well on the 20D. Other like the Sigma walkaround (24-70/2.8) and the Canon tele (70-200/4L,no IS) and the 50/1.8 are more of a challenge.

I can get the 17-55 EFS IS lens to solve the problem somewhat.

But since I am shooting a lot of baby pics of our newborn and our 3 yr old who loves to pose for pics and has lately been learning to take pics on the 20D, I would like to pad the lighting situation. A simple fix seems to be the Speedlite 600 and use the 2 speedlite in conjunction.

For a lot of infant pics, from reading here and previous experience flashes are not the best solution though. So for the time being can folks here suggest other solutions. I have wanted to setup a little studio corner in the basement. I am wondering if there are any good sturdy solutions involving lightboxes/softboxes/flashpoints that would work for me without being a fire hazard? I know very little about these products and looking on Adorama was mind boggling.

Please advise.