My computer used to go into standby and it would be dead silent, but I upgraded to SP2 and since then it will go into standby but I can still hear it like it's on and I've tried closing everything blocking internet traffic, I can't figure out what has changed.

any help would be appreciated.

Thanks.

Is this a laptop? What is the make & model?

Most similar issues that I see relate to laptops and advise upgrading the BIOS.

That would be available from the manufacturer's site.

nope it's a standard PC

XP PRO
2.0 GHZ Athlon 256 RAM, (more in the mail)

it used to work fine and it would be dead silent but I also installed a 200GB hd but it was working fine no sound I mean, until I installed SP2 it seems.

So you had the 200GB installed and Standby was silent prior to SP2?

Can you determine if it is the hard drive that you hear? Or perhaps a fan?

Is the 200GB an additional drive? Is it a SATA? Is it on the same cable as another?
If it is a hard drive that you hear can you determine which drive?

If you want to test SP2 as the culprit you can always remove it from Add/Remove Programs.
Have Show Updates clicked.

I can find no precedent for this issue in my searches

yes, it worked silently before I installed SP2. but it does sound like a fan, but like I said before I couldn't hear it, now I can.

the hard drive is a maxtor 200gb 7200rpm
IDE it's the slave to my 20gb master also maxtor

As I understand it the fans would stay on in standby.

Perhaps the heat from the new drive is triggering a heat sensored fan to run?

Perhaps a fan needs cleaning or lubrication or replacing?

http://groups.google.com/groups?hl=en&q=standby+fans

I have no idea what this could have to do with SP2. Are you running the Firewall? Do you have another? Are you set for Automatic Updates? Perhaps try turning off these features.