Original Question: "Does my ISP suck or is it just me?"
Krankbt,
I think you may be confused about the link speed. Your advertised speed is NOT the download speed as one might think. We (you & I) measure download speed in KiloBYTES (KB). The advertised speed is in KiloBITS (Kb).
Your ISP said 512 max download and your test showed 534 (faster than advertised!)
Translation: 534Kbps download would actually be 65KB