Here is my magnesium thread:

http://neurotalk.psychcentral.com/showthread.php?t=1138

You can use oral forms, but avoid OXIDE types, as they don't get absorbed and are useless except for laxative purposes.
Most of the other versions of magnesium are fairly well absorbed from the GI tract. Aim for 200mg a day dose, elemental to start. Read labels carefully to show what is elemental and what is the total weight/tablet.

SlowMag twice a day is a good one...it comes in a generic called Mag64. WalMart has it affordably (both brand and generic, or your pharmacy can order it.
Some Costcos have the generic behind the counter or they can order it for you---it is very low price there for the generic.
This delayed version is well absorbed.

You can also use a lotion form, called Morton Epsom lotion.
This is at Walgreen's and WalMart or online at Amazon.
This is a wonderful way to loosen up your neck and shoulders if you have spasms or pain there. Applied at night it will help you sleep too. Just use about a quarter's diameter per day if applying it on arms or legs or back, or a fingertip amount on the neck area once a day. You do not need huge amounts of it..as the magnesium in it gets absorbed nicely.