Have you bought something online, ever. Then later found you had to get your receipt to return something or verify it, only to find you misplaced it. Did the order you got have an invoice that was different from the web page receipt you were sent to after hitting "confirm order"?
I save all my online receipts in a special folder on my hard drive. I merely labeled it, web receipts.
After I purchase something online I look for the printer friendly button, and click it.
A new page, usually nicely formatted ,will show up. I click on the pull down menu file. Look for save as,
navigate to my web receipt folder, and save it.
Mind you, in windows making a folder is easy enough,
and some forethought for organization makes things easier to look up later.
Click on the windows start symbol on the lower left hand corner. (usually) on the menu find "my documents"
then after you found it click on it. A folder window pops up, right click anywhere in that window and a new pop up drop down menu might show, new folder. Left click on that, and type in a name like web receipts.
Open the web receipts folder, and repeat, maybe making a folder marked, "2009". (year) and then another with the company name. Maybe "Walmart" or "Newegg" or whatever.
That's basically it. Next time you order something online, you save the web page, and later, if you ever need it It's there waiting for you, and easily found also.
Antonio