Slow performance

Hello,




1. my dell inspiron core i3 laptop with windows 7 home as OS is lately giving problem of getting slow or almost hung for atleast 20 to 30min before resuming the actual speed.
2. this happens after 5 to 8 min of starting the laptop.
3. after that it just becomes too slow to act on any command.
4. if the internet connection is also plugged ,it probably further slows it down.
5. i had earlier stopped all auto updates of the system and other softwares. yet the problem persisted.
6. now i have downloaded the updates from the net . again thers no improvement in the behaviour of the machine .in fact now it keeps sending the message DO NOT SHUT OFF. WINDOWS IS CONFIGURING THE UPDATES or something of that sort..
7. its pretty annoying to see and wait for messages /action for 10 min or more. and then further wait for the machine to get its speed after 20 min.
8. even when shutting down the computer it send s such kind of messages for 10 mins or so depending upon the number of updates .
9. all this is killing me. do i need to throw this machine n buy a new one.
10. pl help