a few steps to diagnose this;
1 - Connect your laptop/netbook to the ethernet port on your sky router and see if its any better - this will establish if its a wireless problem or not
2 - try
http://www.speedtest.net for a more accurate speed guide. - it may be handy to try this at differant times of the day
3 - is your internet slow at peak times 6:00pm until 10pm (ish), if so this is likely due to sky over subscribing in your areas (ive had this with btinternet myself) - this is very likely!!!
4 - Check you do not have any kind of anti virus / firewall / spyware removal tools installed on you netbook / laptop as this can cause a massive slowdown (especially with norton) also check that windows firewall is turned off as ive seen it in the past that it doesnt disable itself when you itstall a new secuirty suit such as norton