I have a Sony Vaio with a hard drive of about 160GB.After getting Vonage it slowed down.How can I speed it up?

It’s pretty slow and especially the internet, any helpful tips would be highly appreciated and only answer if you know what you’re talking about.
Oh, I don’t know why but I should have mentioned the 512 DDRAM instead of the hard drive. It took forever to sign up for the Vonage forum for the test so I pulled out the blue cable and put it back in and cable internet speed again. Thanks for everything. I do have a Motorolla thing for the cable internet and its all fine now.