Downloading/uploading vista problems

Please help

Before I start, please note that I am quite 'dumb' with computers...lol.

I recently purchased two computers with Vista on them. I'm not sure what details everyone needs .... but in basic.... both of these computers do not 'download' things without freezing up half way through.... whether it be emails coming through, windows updates (Gets to a certain percent and then stops, I have to stop the process and then re-install until it finally works its way to 100%), anti virus updates... even just clicking on a webpage I always have to 'refresh' for the page to come up.... sending emails it 'freezes' and so I have to hit send again... this also means that some people get the same email from me twice.

Sorry to be so vague.

It is very, very frustrating.

The same time that I bought these computers I also bought a wireless router system... not sure if that's the problem ??

Have tried friends and the people I purchased the computers from but no one has any idea and can't help.

I am hoping someone out there knows something.

Thankyou in advance

Turned out to be the 'wireless router' .... now have a 'wireless modem' and everything is working perfectly !!