Best Buy component speakers...

My wife received a Best Buy gift card from work and she wants to use it towards replacement speakers in front (both woofers and tweeters).

I am quite unsure how a component speaker change over would be done replacing the factory woofers and tweets up front. Are the factory speakers already set at a crossover? If so, would just replacing the tweets and woofers suffice? Or should I try and install whatever crossover comes with the component package?

If anyone wanted to take a look at Bestbuy.com and see what would work, mucho appreciate it I keep reading two different versions, either is 5.25 or 6.5 size...