Maternity Belt or Support Bra??

Have any of you moms used a support bra (the one that's marketed to go over your bust and down around your belly) for back support during pregnancy, and if so, is it substantial? I have a weak back as it is due to years of working a laborous job in horticulture, and lifting. This is my third pregnancy and I am in the first week of my third trimester and have two other children to care for. My back goes out within the first three hours of the day and I am completely useless. I feel like my hips and legs have seperated and can hear a popping sound when I walk! I know things go haywire down there as joints and ligaments loosen up, but it freaks me out and I am really trying to take it easy. However, someone still has to buy the groceries, run the errands, do the laundry, and general everyday housework. My husband is out the door at 4 am and when is home is very stressed and tired and I hate asking him to do anything. I am looking at the maternity belt online but it looks really uncomfortable and also noticed this support bra that claims to help with back support, but it doesn't look like it would do a damn thing. Do I just get the belt and say heck with the support bra?? Any one used either one?? thanks moms :)