laptop often hangs
Do you mean that the system freezes and is unresponsive to the keyboard and possibly the mouse? ..Or do you mean that the system slows down so much that you have to wait long times between commands from the mouse and keyboard?
usage is normally 70%
That is way too high just for regular computer use; you are running only 2gigs of RAM (memory) and Windows really needs at least 4 gigs to run adequately. That definitely is one reason for the problems. That should be the first thing you do.... increase your memory to 4 gigs whether you are running 64 bit or 32 bit. You should stick with the 64 bit system. It's a far more efficient platform and 32 bit will be eventually phased out of usage. Most new software now is being written for 64 bit systems.
kaspersky antivirus is taking up a lot of RAM
IMHO, Kaspersky is a resource hog and will slow any system. I suggest using the Windows Antivirus and Firewall on a laptop. Windows AV has a good reputation, at least equal to Kaspersky and maybe better, and will not slow your system. Windows firewall is not as feature-rich as some others, but it is solid and dependable and will not slow the system. If you choose to use Windows AV, definitely remove Kaspersky; do not have two AVs running at the same time.