should i build a pc? whats best for Linux Lite 2.0?

[gold_finger]

as you can tell i'm just trying to fix the problem but am scared i will be beating a dead horse if buying expensive replacements to test...

That's the key question for older systems.  Will new components for it end up costing same as cost of a newer (complete) used system and/or will the money be wasted if new part is not compatible with newer system that you might end up needing anyway if fix does not work?

My guess is that your video card in old computer is on the fritz.  If you've got a replacement card already that you can test out, that would be good.  If not, you're faced with dilemma.  Good chance that you'll need to spend approx $75 on new video card and it will be an older version (possibly AGP connector) that is no good on newer systems.  If it doesn't solve problem, then you're out $75 on a part that can't be used on new built or newer used system.  If you buy a new power supply, make sure it is one that could handle your needs if you end up having to resort to building a new computer.

If situation is not desperate at this point, I'd recommend you sign up for Newegg emails and start researching components and their costs.  Sort Newegg search results by those with "Most Reviews", then pay attention to what people write in those reviews.

Also, if Craigslist is popular in your area start regularly browsing the listings there for used computers.  Be careful with Craigslist though.  Take your time and do plenty of research on computers you see listed.  Don't jump on first thing you see that sounds good.  Save copies of listings that interest you and over time you'll get a better feel for what is a reasonable sale price on various models.  Normally, computers take a while to sell and multiple similar computers can be found at any given time.  Know the correct, full specs of any computer you choose to go test out before you go; then carefully check what you find to make sure it really is what was advertised.  Bring a live Linux Lite USB stick with you for the test.  Like rokytnji, I've had my fair share of experience acquiring used systems at really good prices; but if you don't really know what your doing and what to look for, it's easy to get taken for a ride.  Good general rule of thumb on Craigslist, try to decifer which listings are from "normal" people vs. serial sellers with tons of listings for various computers.  Stick to buying from average everyday users who are just getting rid of their old computer because they bought a new one.  You should be able to find pretty good 5-6 year old computers for $75-150 max.

Regarding new builds -- most Intel and AMD motherboards will work fine with Linux.  (AMD boards and their components are less expensive at similar performance points than Intel.  I've used AMD exclusively for a number of years and don't have any complaints.)  Generally speaking, if you stay away from the newest high-spec boards that require/use absolutely newest graphics you're less likely to run into compatibility problems with Linux.  Decide approximate budget and what you need to use computer for, then pick components based on that.  If not a gamer and just need computer for basic use, you should be able to build a nice system for under $500 that will run circles around what you currently have.

P.s.
In new builds, you can usually get away with using some old parts -- DVD drive, hard drive, etc.  If old DVD and/or hard drive is an IDE drive, be careful to make sure new MB supports that -- many do not and only have connectors for SATA drives.