What do you do on the laptop? If you just search the web, there is really no need. Also, a core i5 mobile still only has 2 cores I believe without HT which gives a very minimal performance upgrade. The core i7 would give you 4 cores with 8 threads, but unless you are doing A LOT on a laptop, there is no need to upgrade. To make a web/business machine faster, the issue is normally RAM or HDD. But a quick answer would be, yes, you can put a core i5/i7 in your machine.
Hope this helped!