Trouble restoring my Dell Inspiron 1525

Hi all,

I had a virus on my laptop recently, have gotten rid of it, but my laptop is still pretty slow and sluggish and I want to restore it.

I have followed the instructions, I press F8 when starting my computer and the Dell logo appears. This takes me to the 'start in safe mode, repair your computer' etc screen - I press enter for 'repair my computer' but then it just starts as normal. Which makes me think a) I didnt get rid of the virus. b) I cant do it anyway. c) I rent my laptop, but got it brand new in the box. would my rental company maybe have put a stop on restoring?

Anyway. I dont have the CD because my laptop came ready to go (but in the box), so I cant resore it manually.

Any help would be appreciated, thank you!