Make sure you make backup copies of your current logo files either by copying them to another folder someplace you'll remember or renaming them (for example 'logo.sys' to 'logo_.sys').
Your original 'logo.sys' should be located in your root hard drive directory (C:\). 'logow.sys' and 'logos.sys' should both be in your main Windows directory (C:\Windows).
To install the new ones, simply copy and paste the 'logo.sys' file into your root hard drive directory (C:\). Then copy and paste 'logow.sys' and 'logos.sys' into your main Windows directory (C:\Windows).
Or simply download a logo management program. You can find one at www.freethemes.com.