Presario 2100 notebook

[isterin]

I just purchased a 2178cl notebook (Athlong 2400+, etc...). I've
misplaced my ac adapter a few days ago, and have purchased another
one.

The spec asks for a 90w ac adapter, which is what I purchased. In the
meantime, I have a 75w ac adapter from my other hp notebook. Taking
into consideration, that I don't run any peripherals other than a usb
mouse, would that be sufficient enough for use for about a week, until
the other one arrives?

Also, can it potentialy cause any hardware damage to the notebook in
any circumstances?

Thanks for any help.