to find out computer specs on windows,use the systeminfo command in the command prompt program,
or go to acessories>run and type dxdiag.
a better way of getting specs is the awesome program;speccy,which gives a easy to see GUI but highly detailed information-ranging from each part to what temperature they are running at,it is made by the same guys who developed the popular crapcleaner [now known as ccleaner]-
in own view for linux newbies,it is best to start with a ready to run package; such as linux mint,mandriva,ubuntu or openSuSE,as they all have no fuss visualy pleasing instalations,and are for most people ready to go once the usual settings are personalised.
-the only problem though,if this computer is as old as am thinking,if it had originaly came with XP- it will struggle with these user friendly but bloatware focused distros,ubuntu is probably the least bloated
and from the beginning can be downloaded with any of the major desktop environments so xubuntu may be the best fitting here.
although its a great way for everyone from beginners to experts to learn about linux,dont install it through a virtual machine unless have got significant memory and processing available as the VM shares it between the host and guest operating systems in use.
a dual or single boot with linux is the best option for better performance.
linux has a lot more open source native programs [graphical/GUI and command line based] available to it than windows will probably ever have,including some built from open office so once are sorted with a linux distro,dont forget to check out here,sourceforge or google for ideas,or look through the package manager [such as synaptic].