good consideration - юридически действительное встречное удовлетворение
valuable consideration - надлежащее (достаточное) встречное удовлетворение

Анго-русский полный юридический словарь по ред. Мамулян А.С. /Москва "Советник" 1993г.

--------------------------------------------------
Note added at 53 mins (2004-11-05 14:22:27 GMT)
--------------------------------------------------

Valuable consideration (Law), an equivalent or compensation having value given for a thing purchased, as money, marriage, services, etc. Source: Merriam-Webster Dictionary of Law, © 1996 Merriam-Webster, Inc.
Good consideration (Law). (a) A consideration of blood or of natural love and affection. (b) A valuable consideration, or one which will sustain a contract.



--------------------------------------------------
Note added at 1 hr 0 min (2004-11-05 14:29:52 GMT)
--------------------------------------------------

Good consideration (Law). (a) A consideration of blood or of natural love and affection. --Blackstone. (b) A valuable consideration, or one which will sustain a contract. good consideration
1 : a consideration based on a family relationship or natural love and affection
2 : VALUABLE CONSIDERATION in this entry
NOTE: When used as defined in sense 1 good consideration is the opposite of valuable consideration. However good consideration is also sometimes used to mean valuable consideration. Good consideration of the kind denoted by sense 1 cannot create an enforceable contract. valuable consideration
: a consideration that confers some benefit having pecuniary value on one party to a contract or imposes a detriment having pecuniary value on the other