you already have a 500gb sata 7200rpm drive so it's a fast hard drive. a 10,000rpm drive is technically faster but won't help most apps. if you're creating multi-gigabyte video files, a 10k drive may help a bit, but otherwise you won't notice the overall difference.
run the speed test and tweak test at http://www.dslreports.com/tools to make sure you're getting the broadband speed you're paying for and to tune your connection.
I think that the satas are the fastest.... but wich model? and I have an NVIDIA nforce Network adapter, can I get one that makes my internet faster?