R9200 vs FX5200 is a pretty level playing field, infact all of the cards are.
What people forget quite obtrusely when trying to compare the cards is that there are multiple versions of each of them.
9200 ~ 5200
9200 Pro ~ 5200 Ultra
this actually follows this pattern quite well throughout each of the series of cards.
The Std Editions and Enhanced Editions are roughly speed and power; and despite everyone throwing reviews of these cards beating the other cards; if you ever look at the performance the online reviewers get and what the general public gets, often they favour what 'gamers' at the time are praising. There is usually a difference of around 5-10fps in speed, which if the performance is 20fps then fair enough that is enough to worry.
But when the performance is 70-100fps that 5-10fps really make no odds what-so-ever.
So your choice should really come down to Price & Features.
This is why the FX has been outselling the Radeons 3:1 for the past 12months, even with all the bad publicity.
They have far more features and until recently were one hell of alot cheaper.
It is all well and good to say 'Well i'll just get the fastest card', but when the difference of an R9800XT vs FX5950 ULTRA is around 5fps in Halo quite frankly I'm going to buy the one that is cheaper.
FX5950 in every case is cheaper, quieter and uses ALOT less power (meaning you don't have to upgrade from a std 230watt PSU to 350watt PSU just to make sure your machine doesn't blackout reboot)
This also ends up friendlier on the electricity bill (might not seem like much but that extra £5/month adds up!)
This isn't to mention the stability the cards have being openly compatible with every game not just those that people play the most or are most current, additional feature support, as well as a company support line that *ACTUALLY* responds to problems.
At the end of the day, it isn't just pure performance of a card which should make you want to purchase it. Performance wise the cards are a fair trade between each other... in every other respect, it isn't even a close match.
Athlon64 FX-51 | 1.5Gb DDR2 PC3400 | GeForce FX 5900 Ultra 56.60 | DirectX9.1 SDK | Audigy2 | Windows XP 64-Bit