In Macbeth, to what extent does Shakespeare present lady Macbeth as a powerful woman in Act 1, scene 5?

In the opening lines of scene 5 of Act 1, we learn how confident lady Macbeth is about her power to influence her husband. She has just received a letter from him which informs her of the witches' predictions that he will be king and that he has been awarded a new title, thane of Cawdor, a fact which had also been predicted by the evil sisters. She expresses fear that Macbeth does not have the callousness required to attain the crown by malicious means. She then says:

...Hie thee hither,
That I may pour my spirits in thine ear;
And chastise with the valour of my tongue
All that impedes thee from the golden round,
Which fate and metaphysical aid doth seem
To have thee crown'd withal. 

Shakespeare pertinently displays her ruthless ambition in these lines for she wishes to encourage her husband to ignore all sentiment or conditions which would stop him from achieving his goal to become king.

Later, when she welcomes him home, she wastes no time in informing Macbeth about how idealistic she is. She feels their glorious future in the present, which implies that she is not going to waste any time in preparing for their claim to the throne.

She obviously intends to take the lead in getting rid of Duncan. Shakespeare illustrates her barbaric intention and her devious nature when she tells Macbeth:

...To beguile the time,
Look like the time; bear welcome in your eye,
Your hand, your tongue: look like the innocent flower,
But be the serpent under't.

She has already taken command and advises him to assume a convivial nature and be kind and courteous to deceive others whilst he is, in fact, plotting terrible mischief. Her malicious desire is further supported by the words:

He that's coming
Must be provided for:..

She is ambiguously suggesting that Duncan must be taken care of, not in a kind, affectionate manner, but that his assassination should be carefully orchestrated. To this end, she commands Macbeth:

...and you shall put
This night's great business into my dispatch;
Which shall to all our nights and days to come
Give solely sovereign sway and masterdom.

Shakespeare indicates, in these lines, that Lady Macbeth is, most definitely, a powerful figure. She has no qualms in committing the most dastardly of deeds and is fearless. She is confident in her ability to successfully plot Duncan's murder and, therefore, is comfortable in telling her husband to allow her to make all the necessary arrangements for their pernicious plot, for this will ensure them future glory when they, as king and queen, will have sole command and mastery over Scotland.

Her confidence and power are further supported later when Macbeth expresses doubt about the success of their evil venture and wishes to withdraw from committing the deed. She manages to persuade him by, once again, taking the lead. It is ironic, therefore, that she later commits suicide when the extent of her and her husband's malice persistently gnaws at her conscience and drives her over the edge.