I have windows 2000 server and it is infected by downloader virus, so please tell
Me what to do.

Do you have a system restore feature? When my computer is weird I do that. I'm no expert though, so you may want to wait for one to come and help. :)

If that doesn't work then download the free avg antivirus, reboot in safe mode with networking and install. Once installed, let it download the updates from the internet and scan the drives. Once it is done then reboot and enjoy.

Santosh.Good advice from jham.The virus you say you have,is this one:

Discovered: April 4, 2002
Updated: February 13, 2007 11:42:23 AM
Also Known As: TrojanDownloader.Win32.GetFile, TrojanDownloader.Win32/Erom [R, Downloader.w [DRS]
Type: Trojan Horse
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP

It's "threat level" is described as low,and is easy to get rid of,even though it is annoying to have the virus in the first place.

AVG,ccleaner,Spybot Search and destroy,Adaware,are all good programs to install,to keep your PC safe.I would also suggest installing Zone Alarm Firewall.All these programs are free.If you have these already,my apologies.