This isn't a supercomputer. There are various definitions for what qualifies -- "a computing resource which costs over $1M", "a computing resource which requires several forklifts to install", and (my personal favourite) "the FIRST page of the Linpack 'top 500' report" are the most common -- but this fails to even come close to any of them.
Microwulf is certainly a neat hack -- but a supercomputer? No.
The computer that beat Kasparov had chess-specific processors. IIRC, they could process a move in one cycle--something that normally takes thousands and thousands of cycles.
It's not your fault. He does not know what he is talking about. Gflops are just port of what makes a super computer a super computer. Like most computing systems Latency, Bandwidth, RAM, etc are all part of the equation.
EX: A nVidia 8800 Ultra performs around 576 GFLOPS on 128 Processing elements it costs ~$615 today which is ~1/50 th his cost per GFlop numbers.
But it would not on the top 25 list for June 2000 even though it has more processing power than the 537.6GFlop Nagoya University system. It's lacking in other resources which would limit it's ability to run the standard supercomputing benchmarks.
Microwulf is certainly a neat hack -- but a supercomputer? No.