Are you going to carry the laptop a lot ?

Do you care about weight, size ?

If the anwsers are Yes, then, you should go with a 15.4" laptop.

I tell you this because I hate 17". I find them too big, too heavy, bulky and not as easy to carry as a 15.4" laptop.

But if you really want to with a laptop of that size, then, this HP seems good.

The differencebetween the T5300 and the T5500 isn't noticable. Maybe if you do a lot video encoding or file compression tasks you'll notice a little difference, but it's not like comparing a T2300 of the first generation of Core Duo with a T7500 of the latest Santa-Rosa platform where the performance gain overpasses the 250 %.

You should also take a look to the future Dell Vostro ( in replacement of the actual INspiron line ). According to Wikipedia, Vostro laptop are coming on the market on June 26th.