Another thing to think about.... an office chair that can go up or down is a must for me. I am 5'2" and I sew at the height of a regular dining table, which is the same height as the normal sewing machine cabinet. This, also, allows me to put a folding table up close to my sewing table and let it help support the weight of a quilt when I am sewing the longer rows or putting the binding on. Or, I can use the extra space as ironing area or trimming area. When you start changing the height of the typical table, it can throw other things off.
Now after having said all that, if you can do a cutout for your sewing machine and bring it down to level with the table, then that is the best solution. This is one way
https://www.youtube.com/watch?v=mbE48Saa-Pc
Another idea
http://www.instructables.com/id/Make...able/?ALLSTEPS
There are more out there. I searched for "flat bed table for a sewing machine"