I'd go here http://support.microsoft.com/default.aspx?...kb;EN-US;221829 and do what its says about formating etc, then have another go before you get too much installed and have to waste it all by maybe later on having to reformat for some reason or other.
If you want to wait for more answers I'd also post your machine spec' besides the memory.
As for your question on upgrading, well this is as long as a piece of string e-machines did alot of onboard stuff like video and sound cards so it all boils down to money and what you want to use the machine for now and say in a year from now.
Bookmarks