Deploy web part in a virtual server by developing a Web Part Package file(.cab)

1. Create a Cabinet Package(.cab) using Cabinet Manager 2003;
The cab package will contain at least web part assembly file, web part description file and manifest.xml.

2. Run the following command on the sharepoint server machine;
    stsadm.exe -o addwppack -name path_to_web_part_package_file [-force]
[note: the -force parameter will be used to update the web part to the newest version]
This installs the web parts contained in the .CAB file into all virtual server library.

3. Delete the web part;
   stsadm.exe -o deletewppack -name path_to_web_part_package_file 

Adding Web Parts from a CAB File to the Server Gallery
       - from SharePoint Portal Server 2003 Administrator's Guide
You use the command-line tool Stsadm.exe to add the Web Parts in a Web Part Package (in CAB file format) to the list of Web Parts available for a server. The following operations are available for Web Part Packages in Stsadm.exe:

addwppack — Adds a Web Part Package to the Web Part gallery for your server or server farm.
deletewppack — Removes a Web Part Package from the Web Part gallery for your server.
enumwppacks — Lists the Web Part Packages currently in the Web Part gallery for your server.
These operations take the optional -url, -filename, -name, -farm, and -force parameters. For example, to list the Web Part Packages that are currently available for your server, you would use the following syntax:

stsadm.exe -o enumwppacks
To add a new Web Part Package to your virtual server, you would use the following syntax:

stsadm.exe -o addwppack -filename <path to file> -url <URL>
You can add a Web Part Package to all virtual servers on a server by using the -globalinstall parameter. To do so, you would use the following syntax:

stsadm.exe -o addwppack -filename <Web Part Package filename> -globalinstall
If you have already installed a Web Part Package to a server, and you want to distribute it to other servers in a server farm, you can use the following syntax:

stsadm.exe -o addwppack -name <name of Web Part Package>
You can use the -force parameter to overwrite an existing Web Part Package with a new version, or to repair a Web Part Package by reinstalling it.

To delete a Web Part Package, you would use the following syntax:

stsadm -o deletewppack -name <name of Web Part Package> [-url <url>]