JOEL - The Holy Ghost is a spirit, but there is a spiritual influence that eminates from Him affecting all who faithfully seek wisdom from God. The Holy Ghost (also called the Holy Spirit or Holy Spirit of Promise) is the third member of the Godhead and can be a constant companion for those who have been baptized and have received this gift by the laying on of hands.

"Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost." (Acts 2:38)

"Then laid they their hands on them, and they received the Holy Ghost. And when Simon saw that through laying on of the apostles’ hands the Holy Ghost was given, he offered them money," (Acts 8: 17-18, Acts 19:6)

The light of Christ(also called the Spirit of Christ) is the spirit that eminates from Christ like light and gives all men the ability to know right from wrong.

"Wherefore, I beseech of you, brethren, that ye should search diligently in the light of Christ that ye may know good from evil; and if ye will lay hold upon every good thing, and condemn it not, ye certainly will be a child of Christ." (Moroni 7:18)

"For behold, the Spirit of Christ is given to every man, that he may know good from evil;" (Moroni 7:16)

"That was the true Light, which lighteth every man that cometh into the world." (See John 1:1-9)

The "Light of Christ" is given to everyone regardless of their beliefs, while the Holy Ghost is reserved more for those who seek to do and understand God's will and His Gospel. The source for both is from God.
Occaisionally the term "Holy Spirit" might also be used when speaking of the "Spirit of Christ". The scriptures are not always precise in the use of such terminology, which can lead to some confusion. One must consider the context in which the term is used to understand which "Spirit" it is talking about.

TANYA - This was cut and pasted from one of your answers previously.

Q: If Gods are individuals who have passed through mortality and have progressed to Godhood, how has one The person of the Trinity (the Holy Spirit) attained Godhood without getting a body? (see Acts 5:3.4)

A: Special Case. The Holy Spirit can not dwell inside someone if He has a body. When His existence as a spirit is no longer necessary He may some day get one.

I did not think the Holy Ghost's personage dwelled in people, I thought it was His influence. If he can dwell in people like you say above, how then can he only be one place at one time?

JOEL - Normally the Holy Ghost's personage does not dwell directly inside people; as you say, it is His spiritual influence which does. However, being a personage of spirit He could dwell within one person if He wanted to. This refers to the scripture which says:

"The Father has a body of flesh and bones as tangible as man's; the Son also; but the Holy Ghost has not a body of flesh and bones, but is a personage of Spirit. Were it not so, the Holy Ghost could not dwell in us" (D&C 130:22).

Actually, exactly how the Holy Ghost dwells in us is one of those things that no one can really understand.