I usually avoid free graphics for 2 reasons - they're usually low quality (as you've found), or if they're decent quality, I fear they've been scraped from a paid site and I'd rather be legit.
I'm currently using bigstockphoto.com and istockphoto.com. Both sites offer most images in several resolutions - you can usually get away with the lowest res for web stuff. istockphoto seems to have better photographers, but also carries higher price tags on some of the images, so I usually check bigstockphoto first.
Prices vary by image, but most are very reasonable. They also offer subscriptions which might work better for you, but I just buy credits then spend them when I want.
Re: correct place for this question - yes, I think so?? LOL Sometimes I'm not sure either - some questions are harder to categorize than others. If a more experienced moderator thinks it fits better in another forum they'll move it for you, no worries.