想問如果業主轉租約....

As you have been in the premises for some months and the rent had been paid and duly received by the landlord, the obligation of the landlord should be regarded as stated and as to be performed in the old tenancy agreement. If a new agreement has to be made, you have the advantage to have the terms in your favour after negitiation. However, it is doubtful that the landlord could make a new agreement with you as the premises has been sold, assuming with an existing tenancy, to the new owner. The date of this 'new' agreement is then after the date of selling. In this scenario, this issue must be communicated with the new owner for affirmation.
It is strongly recommended for you to negotiate this issue with the landlord / new owner or you have to seek a lawyer for a legal opinion.

現租約(即使是租約書)對新業主仍屬有效，根本唔駛理佢地，新業主、舊業主也好，影响你權益嘅一於不理，如果新業主向你收租亦須給你業權已轉至其名下之証明。

As the old lease did not have stamped, then you should ask 1.new agreement is the same monthly rent & the start date of 死約 is still 12/2007 or new start date 2.if same monthly rent & the start date of 死約 is still 12/2007 but only the name of owner changes, then you may not have any compensation because you have no loss.
But if the owner tells you that the new lease is new monthly rent (increase) & the start date of 死約 is May 2008, then you firstly go to 'stamp' dept to stamp the old lease because if you want to sue him/her in the court, the government oly allow the stamped lease as a legal document, then you tell your owner that he/she breaks the contract, ask him to compensate the difference between the old lease & the new one except the rents of 12/07 - 4/08.
If he/she wanted you to move, then he/she may compensate your 'removal' fee & the difference between your new lease in the new flat & the old lease.

2008-04-04 02:17:18 補充：
But most of owners mean only to change name in the new lease, all the dates & money are the same. So you & he/she do not have any loss.