increased lag
Yea, go to start -> run -> Type: msconfig -> startup tab check out what all is starting up, this startup is empty on a fresh install. Some drivers and what not might be in here, but you should be able to disable everything in your startup without any problems. Just make sure you know what you are disabling.
After this I would consider checking your computer for viruses / adware / trojans and shit.
Ad-Aware SE Persona: http://www.download.com/Ad-Aware-SE-Personal-Edition/3000-8022_4-10399602.html?tag=lst-0-1 Spybot - Search & Destroy: http://www.download.com/Spybot-Search-Destroy/3000-8022_4-10401314.html?tag=lst-0-1 Norton Anti Virus: http://www.download.com/Norton-AntiVirus/3000-2239_4-10592478.html?tag=lst-0-5
There are a few other nice tools out there, just do some googling.
Also, it could be your router / modem. Try switching off your router and modem for 1 minute, "1 minute to drain out".
If none of this fixes the issue I would consider contacting your ISP support team and asking them about it. They will tell you to do some bandwith testing and give you results and/or tell you that they are doing some other shit and it will be fine within a day or so.
Also check out your process's currently running. Anything that is labeld SYSTEM, LOCAL SERVICE, and NETWORK SERVICE leave alone. Anything that is labeld "Your User Name" you should be able to end without any trouble.
Also make sure you are all up to date on drivers and software. Some times that can fix several issues! :)