Use the
speedtest.net website to test your Internet connection and see if you're ISP is haping your traffic. Do it in the morning and then the evening. What downspeed is your laptop getting, is it on the same line as your desktop PC?
And yes a hardware firewall will slow your connection down. Motherboard firewalls are pretty crap compared to a dedicated standalone hardware firewall. Use a software firewall like ZoneAlarm instead unless you use Vista.
BTW, Kb is kilobits and KB is kilabytes. The two are very different. There are 8 bits to 1 byte, so 7KB/s = 56Kb/s.