I do not believe you can download evaluation copies of SilkTest at all. You have to contact Segue directly and ask for an evaluation copy to be sent to you. This is the case becasue they need to issue you a temporary license in order to use the product.
You can download patch for upgrade only if you have old version of silktest. Segue giving silktest for evaluation to the customer and need to contact them. If you want to try other tool as winrunner or rational tool go to their site and download for evaluation. www.rational.comwww.merc-int.com