This is normal if you are on adsl since your speed depends on your line quality (distance from the exchange, age of the phone line, connections between segments of line, insulation etc...).
Go to your modem's page and look at the sync rate, if it is similar to 450KB, you have nothing to worry about. You can try increasing the speed by changing the speed profile (at least for my isp), but for that to work you need high snr margin and low line attenuation. You can also try coding gain, set it to 7 or Inc2_5
Also do an isolation test to test for line fault. Unplug every device from your phone wall socket and plug your phone directly into it. Listen to the headset for noise. If there is noise, you have a bad line. Call your isp to fix it.