Five years ago the GF2 TI500 was a high end card, the GF2 MX400 was a poor cousin, I know, I had it as well.
The MX models that followed were also poor and ATI gained a good following during that period. GF4 TI 4xxx series brought some grunt back to nvidia, and they were superceded by the 5000 series, however, the low end models never were as good as the previous generation.
This included the rather poor performing 5200 cards which were a little bit better than the GF4 MX440's which were popular then.
ATI had the 9600XT and 9800XT then and they were far superior, further strengthening ATI's popularity. The 5200 was very poor in comparison, and was, at it's release date, only really popular because it finally brought some budget performance to the market.
Many people got their first taste of reasonable graphics with the 5200 which may explain why it got such good raves and was a relative success while it was actually a very mediocre card when it was released. Here is an old chart showing the food chain about 3 years ago, note the very poor performance of the 5200 by comparison to it's contemporaries of the time. Note there was a 5200 ultra which performed a bit better but you don't hear of many users owning them.

The 5900 series of that GPU type was released then also, it included a 5900XT model which could be overlocked to or near 5900 Ultra speeds, that was the card to get if you were on a budget at the time. However, the 5900's were still expensive by comparison to the 5200 which nVidia touted as the mainstream graphics card.
The 5900 series was top dog for a very short time and because of this, it got a bad rap it didn't deserve. it was simply out-teched very quickly by ATI products. The Radeon 9800XT was, in fact, still a very powerful contender when manufacture ceased due to it's old DX8 vintage. Many cards were and are still being released that can't hold a candle to the 9800XT of that period.
Now, we've been thru a more modern period where ATI showed us the X800 series and the X1800 series, while nvidia progressed with it's 6800's and 7800's, all this with a change from AGP to PCIe.....
Technology moves so fast in PC's, you can easily and unwittingly buy into old or poor technology unless you really have your finger on the pulse and are willing to shell out a bit of cash for it.
There are areas where you can cut costs, but core components, and especially the video card, need to be the best possible for your budget if you want good simming performance.