Hardware Help

Hi

I have a the Datel 4gb hard drive and X2 battery add-on pack.

I am thinking of replacing them as the HDD does not work too well with 1.5 and is rather slow.
I know there are cheap 4gb memory solutions at the moment but would rather wait for an 8gb memory stick .

However, I'm having trouble finding a better standalone battery than the X2. Is there such a thing?
As far as I know, there are no batteries over 3600 mAh which don't count in the original battery as well.

8 gig memory sticks arent going to work on 1.5 according to sony.