If you Google for the comparison you will read several differing opinions. Lots of people did not like the new Ribbon style when they changed from 2003, it is a personal choice thing. Most say that recalculation in Excel 2010 is faster than in Excel 2003 and they like Powerpoint integration better. Spreadsheets made in 2003 can be read in 2010 but not necessarily vice versa.
Personally I am pleased with the changes, but if you have the space available on your laptop there is no reason why you cannot have both on it. Get used to the differences and then make up your mind later which you prefer.
I presume that the version of Office 2010 that was installed was a legal one and that it has been activated correctly. It would not be good to choose 2010, delete 2003 and then find 2010 will not update etc.