im running a ADSL modem 512K downstream 128K upstream my adsl modem is DSL-302G i have no p2p software i've checked for spyware and adware nothing found no viruses nothing. My speed used to go 54.1 KB's when downloading but now it's going 28 KB's and lower whats the
1st of all 54kbs is slow compared to what i get out of my 512. i get around 62kbs. but any how this may not be the case but this is my idea. you isp shares its speed between users, during offpeak times speeds will be faster and during onpeak times speed will be lower. If you have downloaded a lot then they can sometimes reduce your speeds as to allow other users who have not downloaded so much to enjoy the benefits. this may not be the case, i would recommend going to www.testmy.net and running the smart scan this will tell you your speed and tell you if it is below average and by what percentage for your service provider.
also do an online virus & spyware scan with this link http://housecall60.trendmicro.com/en/start_corp.asp