The fact that all of my searches on the Internet for "showwnd.exe" say that it is a Trojan and should be removed has caused me lots of grief. It took me awhile to stop trying to remove it. I finally realized that this file was probably legitimate when I restored my Windows XP Home Edition from the Recovery CD provided while NOT CONNECTED to the Internet and this file was there and it was in the startup sometimes too. This is a clean emachine hard drive from scratch that I am talking about where I completed wiped the hard drive and have one partition from the recovery CD and have not connected or installed any programs whatsoever. Totally clean restore. I am sending this from work because I thought I still had a virus until I found this article today. Tonight I can actually start using my computer again.
I did have some spyware and viruses but I have come to believe this file was not one of them.
According to this URL on Gateway (which owns Emachines too)http://support.gateway.com/s/issues/2-1945178247.shtml
"Affected Products: Software
Affected Operating Systems: Windows® XP
ISSUE: The computer may contain several suspicious entries in the startup group or in Add or Remove Programs.
oobeflagnetscape0 is in Add or Remove Programs and may be listed as being 4GB in size.
PrismXL is listed as a running service.
rss_upd is in Add or Remove Programs and may be listed as being 4GB in size.
ShowWnd listed as a startup item.
RESOLUTION: The Oobeflagnetscape0, PrismXL, rss_upd, and ShowWnd entries that may have shipped on a Gateway computer are not Spyware or virus programs and do not harm the computer. There is a possibility that a Spyware or virus program on the Internet shares the same name, however they are not shipped on a Gateway computer and Gateway has no affiliation with such programs. The entries that are from Gateway are harmless and can easily be removed. Each entry has a different removal procedure. Scroll through the following list for removal steps for the corresponding entry. "
Showwnd is included with the Chicony keyboard software and is used by the software to stop the keyboard driver's taskbar entry from reappearing. It is not necessary to remove the keyboard software, however if you wish it can be removed through Add or Remove Programs. "