Depends on how far you have to walk at each end and how much you have to carry. If it's not excessive, by all means, take the MRT.

It's liberating to have a netbook. All the stuff I need for meetings (excluding papers, which I sometimes just carry in a folder) fits in a small 6x9 bag. In fact, if the papers I'm carry aren't legal documents, I just fold them up and stuff them in the bag, too. I don't commute anymore, but if I had to, I could.

As for rush hour issues with the MRT... leave earlier, and buy yourself a set-value card, one that'll last you a week or so. Save your car for days when you'll really need it, like rainy days or shopping days.