The demo at oemr.org is a stock release of OpenEMR 2.8.0. OpenEMR 2.8.0 does have some minor bugs that have already been fixed and available from the SourceForge download site.
It depends a lot on personal preferences. The “tar balls” can be opened in Windows. You have to be a bit careful because the end-of-line characters are different in Windows and Linux. Linux uses a \n and windows uses a control M.
Winzip can open the ~.tar.gz (~.tgz) files but there is a setting in WinZip that breaks the linux lines inappropriately. This has be turned off to open them correctly.
OpenEMR runs on Windows XP professional and Windows 2003 Server.
Your life will be simpler to learn to use Linux as a server. What distribution do you have?
Most full (possibly all) Linux distributions come with Apache and PHP already installed. The smaller ones like Peanut, Feather, and DamnSmall Linux will not have Apache. All of the major distributions SUSE, Debian, Fedora, Fedora look-a-likes, Ubuntu, Gentoo, and others have Apache installed or easily available. (RedHat is still around but the free version has not been maintained for about 3 years.)
Apache takes very minimal configuration to operate. In Slackware I just select to run Apache and PHP during the installation process and the server is already and running when it comes up the first time.
I do make one additional change to the Apache configuration file (need to add index.php to the list of recognized index files).
Your next steps depend on how badly you want to learn more about Linux. :-) If you have the time and desire, you should set up Apache with PHP4, download the tarball and read the INSTALL file for initial instructions.
Otherwise there are consultaints like Yours Truly. I thought there was a list of them at www.oemr.org but I don’t see that right now.