According to yarndex.com Microspun is a DK weight, while the Bernat Satin Sport (I'm working with it right now so the label is right under my nose!) is slightly lighter - sport weight.
Not a huge difference - apparently the Bernat is 221 yards for 85 grams, and the Microspun is 168 yards for 70 grams... The recommended needle size for the Bernat is 4mm, but the Microspun is 3.5mm, so make sure you swatch! (I hate swatching...)
I do like Bernat Satin Sport, and as far as Michael's goes I think it's a good bet! Hope I'm slightly helpful... Good luck!