Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.
More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.
This family of downloaders use XMLHTTP control to download and ADODB.Stream control to write malware on the vulnearble machine, often combined with some other vulnerabilty that allows the downloader to escape from the Internet Explorer internet zone.
Typically SillyDownloader replaces the Windows Media Player in order to make sure that the downloaded component gets executed.
The downloaded component usually contains an another trojan or a backdoor.
Further information about ADODB control is available from Microsoft at: https://support.microsoft.com/?kbid=870669