A friend is trying to install Whatsapp to her X3 and keeps getting "insufficient storage".  The apk downloads ok, but won't install.

According to the specs, the  X3 has 256MB RAM, but when we go into Settings>Storage, it lists "SD Card  1.83GB/1.46GB free" and "Internal SD 17.96MB/17.96MB free".

Does this mean the phone only has 17.96MB free for apps? She has already moved photos etc to the 2GB SD card, and is going to swap that one for an 8GB card, but Whatsapp won't run off an SD card anyway, apparently.  Is there any way she can free up enough space to install and run Whatapp?