Preinstalled Windows 8 most generally is "Windows 8" which is a "basic" version with limited capabilities similar to the "Home Basic" versions of some earlier versions.

If you want a useful OS for a desktop or laptop, it's almost mandatory that you upgrade to "Windows 8 Pro" to get all the functions that are advertised/reported. (It's unclear whether the Pro version is much better for little toy machines.) Some machines can still be purchased with Win8 Pro preinstalled, and nearly all builders offer an upgrade to the "Pro" version.

While new machines still often have only the kiddie version preinstalled, Microsoft recently announced a price cut for Win8 Pro, back to the same price as Win8. No information on whether that's a special offer for a limited time or a permanent change. Check with BOTH Microsoft and with whoever sold you your new machine for the best deal you can get.

For all recent versions of Windows all of the possible versions are on your machine or on the installation disk. All that's needed to switch from one version of WinXP - to another Win8 - is a new "registration number" (call Microsoft to get it) that turns the features on or off. You can't go from one OS to another (e.g Win8 to Win7) that way but should be able to turn on Win8 Pro if you have the basic Win8.

Many builders offered a "downgrade" to let you switch back to Win7 when the first Win8 machines appeared, and it's fairly easy to step back. I haven't looked recently at how many manufacturers still offer the downgrade but if yours does, it usually is cheaper to get it from the same place where you bought the machine.

For runninng "more advanced programs" the most important machine differences are larger and faster Hard Drives and MORE RAM MEMORY.

The best newer and bigger hard drives may use a different interface that will require installing a driver card, and if you don't have a slot to put it in you may not be able to install them internally; but you can still get a "big enough" internal drive with an older interface and use good USB external drives for all the data storage. Since anything external may get bumped around, I recommend something specifically for "Portable" use, but if you have a cleaner desk than I do you might be okay with a "backup" device. USB Drives may be slower than you like if the machine is "old USB," but for the most part it's workable. You may be able to install a newer USB interface card if the speed limits of an older one are too much of a problem.

If your old machine has only 32-bit capability, the amount of RAM that you can install theoretically is lower than if it's a 64-bit macine; but the myth that you can have "all the RAM you want" by going to a 64-bit machine is a false one for the most part, since the BIOS must also support the amount of RAM you install. Some cheap machines will not support any increase in what they have when you buy them, which is rarely but occasionally as little as 2 or 3 GB. Most machines, even in the "bargain priced" range come with 4GB or 6GB and have BIOS support for a maximum of 8GB. A 64-bit computer that supports more than about 8GB will be ... "expensive."

We have two identical Win7 desktop machines that came with 6GB installed. Lin still has no problem with hers at 6GB, but I had to kick mine up to 8GB, the max supported by the BIOS on these machines, to get rid of an "insufficient memory" popup that became a nuisance. A couple of other recurring problems may be an indication that 8GB isn't really enough, but that's as far as I can go for now.

Most RAM upgrades in Win7 and later machines will require replacing ALL the RAM, because of the limited number of slots available. I have NEVER seen a case where buying from the RAM makers was more than half the price of getting an "upgrade" from anyone else, but check what you can find. (I used Crucial most recently but there are others)

Newer machines are much more limited as to what improvements can be made, but if you're not happy with what you've got you do need to take a serious look at what you can do with them to make them functional. A crippled computer can sometimes be cured (or at least given a prosthetic it can limp on). If you bought a toy, you may have to just get a better toy. Everybody out there has lots of new toys.

John