My DW and I had to consider this exact same issue, and in the end we went ahead and had kiddos anyway.
In the past, it was standard advice to tell PwMS to not have children. My personal take on it is that we are on the verge of some huge breakthroughs in MS treatment within the next 5 to 10 years (even though a true "cure" is probably not coming in the short term), so this advice no longer automatically applies, especially for those who have RRMS as opposed to progressive forms of the disease.
Take a look at the clinical trial pipeline - one good site that grew out of a thread on this forum is http://mspipeline.wordpress.com
note that there are around 100 drugs in trials now...including quite a few which are "off the shelf" substances such as hormone treatments, statins, and cancer chemo drugs...100 drugs in trials for a disease that the last 15 years of so-called "progress" have given us about half a dozen drugs to treat...
My belief is that anybody with early stage MS today, provided that they can hold it together 5 more years or so accumulating no to minimal disability along the way using today's drug regimens, should have treatment options to "freeze" future progression of their disease.
As an aside, I would certainly NOT avoid having children, if that's what you decide to do, because of the fear of "passing" MS to the next generation. There will be plenty of treatments (or even possibly a vaccine) for it 20 or so years down the road when its likely to become a problem for any children you have now.
The only valid reason to not have children is that you are afraid of your own ability to care for them, and as I've said above, I think for most RRMS'ers its unlikely to be a problem unless one has very serious disease / disability already.
Bear in mind, with or without MS, there's still plenty of bad things that happen in life that are beyond our control!