How to make a Gateway DX4200-09 into a decent gaming rig

evga are crap, don't touch them. I wouldn't describe XFX as cheap either.

 

Your ram is fine, I would suggest you change the power supply first and get the machine running again, then download the latest driver for your new graphics card, (don't install it), uninstall the onboard graphics driver, shut down instead of rebooting (reboot when it asks then turn off when the computer starts up again before it reaches the loading windows screen), put the new graphics card in (make sure you connect the power connectors for it) and move your monitor cable to the new graphics card (you might need an adaptor, there will be some in the box with the card). Start it up again and install the drivers for your new card, then reboot. Most motherboards will automatically disable the onboard graphics when a plug in one is present.

 

correct about the PSU.

Video card is a case of unscrewing the plates in the back of the case and removing them (the top two blanking plates), lining the card up so the contacts go in the top slot on the motherboard, pushing it firmly in so its seated well and clicks in, then replacing the screws and plugging in the power connectors (6 pin on the power supply, labeled PCI-E). if the card needs two power connectors and there is only one on the power supply, you will have to use the adaptor provided with the card, just make sure the two four pin plugs you need to fit into the adaptor aren't on the same wire if possible.

 

that's not the video card slot, that's a PCI slot (for everything else). The video card you are currently using isn't a card, its a chip on the motherboard. The new card goes in the long black slot at the top (just below the processor cooler). If you describe the sockets on the backplate of the card that's already installed, I'll tell you what it is.

 

I'd recommend downloading a linux liveCD (OS runs from the CD and nothing gets installed) if you want to try linux. Just don't judge the speed of it, it will be very slow as its running from a CD; a real install would be much faster.

Partitioning a running system and dual booting another OS is generally considered to be an advanced topic; I don't know of any free programs that can repartition a drive without destroying all the data on it; aside from fips (free indestructive partition splitter) but I really wouldn't recommend trying that as its an extremely difficult program to use. Commercial programs that can repartition without data loss include Paragon Drive Manager, Paragon Partition Manager and Acronis Disk Director Suite.

 

open source is fine...

 

that's specific to linux not open source in general. windows software will not natively run on linux but there are virtually always ways and means to run it; whether via progams like wine or full blown emulation using VMs.