Continuing with the flywheel effect, this is how you make a "but it's not as good as the latest Windows/Adobe art machine" for free or almost free. I said almost free.
I have an older desktop PC, not the most powerful. I took it all apart to clean out the dust bunnies. Then I put in at least 1 gig of RAM. WinXP does not run it's best with less (512mb), Linux runs OK, but more is better. I put in a CD player, a burner is better and a DVD combo is better yet. Don't worry if you aren't a parts collector, the local PC shop can sale you a used PC at reasonable cost (probably with XP on it already).
Hard drive should be 20 GIG minimum, most operating systems take up 4 to 8 GIG, you'll need room for personal stuff. Bigger is better (more storage space). Make sure the motherboard has sound and video built-in or you will have to have PCI cards for both. I am not a gamer so I don't worry about high on the hog video cards, an average one will do, unless you got to have it. Ethernet built-in is good else another PCI card for that. If you can get USB keyboard and mouse, they are nice but standard PS/2 will do. Get rid of your mouse with a ball, the optical mouse is better for computer art.
When it is all together you have a basic, no frills machine. If you gots XP, OK, but support for XP is getting scarce. I did mention almost free. Use XP if you have it and can deal with it. I offer Linux that comes in various styles and configurations, Ubuntu Linux in particular. Now if your PC is skinny on resources try the Xubuntu version of Ubuntu, more beefy PCs can deal with Ubuntu Standard or Kubuntu if you must. Don't look at me to explain here, get your Google search on and inquire. Yes Linux is just like XP, only different. Like but different. Linux is not Windows and will 'NOT' run Windows software natively (out the box).
OK, you got your used, pre-owned, refurbished, rebuilt from parts PC. Most people can go to the PC shop to get XP installed if they can't manage it. Linux is easy enough to install yourself if you are tech savvy. But unfamiliar stuff is awkward for first timers. PC shops can be Windows centered so you might have to inquire for knowledgeable Linux help. Find a geek if all else fails. Ubuntu is downloaded as an ISO file, burnt onto a CD. It is a "live-CD" which means you can run the system off the CD without installing on your hard drive. This is great for trying it out before installing and seeing what is included on the disk. You can't use the Ubuntu software repositories without installing Ubuntu on your hard drive. Installation is a click of an icon if the hard drive is prepared. Yeah, time to call a geek.
Now, once your operating system in installed and you have internet, you can take advantage of the free open source software (especially art stuff) on the net. For XP systems check out www.webi.org for the free open source stuff. For Linux, each Linux version maintains a repository of compatible software that will run that is internet accessible via an included software management utility. Synaptic is one and another is Ubuntu Software Center. Hey click the icon and you are there. Install GIMP, Inkscape and other apps if you want them. They are easy to install and remove if you don't want them. Being in a repository means they are malware-free, not trialware, not feature or time limited, the real stuff, but they are in various stages of continued development. Don't kid yourself, even off the store shelf software is like this. Yes, things get better with time after all these years.
The end result is I have an artist oriented PC that I didn't pay much more than for used hardware options, a blank CD and time to download-n-burn and install. I can do Cad, paint, draw, illustrate, edit photos, do multimedia projects for free. Now if quality is an issue, no one is stopping you from moving on to more so called pro-ware. But with free open source software, no one is stopping you from starting either. Getting to work your ideas "now" is the point. Start now, perfect and go pro later. I shouldn't suggest going pro requires commercial software, but if you are doing commercial work, using what other commercial workers are using makes you cool in the job market. I am a free-range artist so I can use what I please. So in that vein, I recommend open source art software to cut your teeth, get skills, do art stuff with low money outlay. With the quality of open source today, you may not even want or need commercial software, use it then you decide.