I'll give you my reasoning. The i5-520m vs the i5-540m speed difference is minimal at best. Look at any benchmarks for PC/OS X whatever. Passmark etc, you'll see it's not worth the price difference. the 520m is a very good processor, it's not worth the upgrade to 540m at all, only time you ever see that difference in speed is if you're encoding video and even then it's fairly minor. Definitely not value..
as for the HDD, that's up to you. HDD are cheap and probably even cheaper if you bought it yourself and upgraded. Or like someone else said, save your money and get an SSD. Or go with th 320GB and replace it with a $130 500GB momentus XT for some faster boot speeds and some faster app loading.