i've installed W7 professional but there were not IE8. I've done as you said but couldn't find IE8. Can you tell me more, please!
It should be included with all windows7 operating systems. With control panel set to large icons. All you need to do is go to: Control Panel>Programs and features> Turn windows features on and off (it's on the left hand side in that blueish bar)>check mark internet explorer8 (it should be the third choice in the list)>hit OK and windows does the rest.
Let me know if that works for you.