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That Dolmar saw is much better made, but sourcing parts may be more of a challenge. The MS170 is a bloated, plastic piece of crap, in my experience.
As a new operator, I think you would be better suited with a new saw than an old one, unless you have a really strong inclination toward tinkering with small engines. You should, no, must, make sure you get proper protective gear, also. DO NOT skimp on this!
If I were advising a new sawyer, I'd suggest they look for something like a used Stihl 026, set it up with a short bar (13-16") and then have them read up a lot on cutting best practices. This way they'd have a solid machine that can be had at a good price, that you can get parts for anywhere, and that is a proven and indestructible design.