Could any one help me?

I have 1.43 gb for installable applications.

This is strange considering I haven't really downloaded that much. I also used the Nokia GUI to update/restore my device and after this I have no applications installed but still only have 1.43 gb free why did it not go back to 2 gb.

How can I delete what ever is taking up the space?

Thanks in advance

Any one?

Any one atall?

It's not only applications which use this "Application Memory", There's also some caches and indexes and I believe emails, SMSs and such.

But NSU doesn't touch Application Memory space. All of your previously install application files are still there. I wouldn't worry about it, if you install the same applications again files will be just overwritten and no space is lost.

I was under the assumption that the installable application space was only for installing applications

I think you can set the App Memory to as how much you want.
I'm not sure how (I don't have a device yet)

plz explain that to me ,do I have only 2 GB to install applications and games in N900 ??

This is what I gathered that the 2 gig is for Applications only.

thanks
but can I expand this space to more than 2gig?

IIRC, the 900 comes with a 2 GB partition for /home. /opt is also symlinked to that partition somewhere. There is a small (256 MB?) partition for / (root) and all the rest of the big flash is allocated as a FAT partition that's mounted as ~/MyDocs. This is what is unmounted an made available as USB mass storage when you plug in. You could repartition, but 2GB is quite a lot of installation space.

Additionally, large programs can put their data files in the twenty something gig partition if I'm not mistaken. This is probably what most games would do, since they can easily be hundreds of MB in size and are mostly data files.