Under SETTINGS -> MISCELLANEOUS
Deleted the relative URL from the "Store uploads in this folder" text box and entered a full URL under "Full URL path to files" (ex., http://images.domain.com) and clicked on the Save Changes button. Upon refreshing, the full URL has disappeared.
By the way, the upload of images to a different subdomain (ex., http://images.domain.com) when creating new posts or pages shall work inside WordPress, right? -- i.e., without me having to FTP images before using them within posts or pages, correct?
EDIT: WP version shall read 2.7 Beta3 (entered it that way), not "2.73" ;-)