I doubt you will find the PNY model seen at the link here for under $1000 at EBay any time soon. http://www.newegg.com/Product/Product.aspx?Item=N82E16814133189 This one only runs for about...?
$2,399.99!
!!! 
And just what reviews are those? While some reviews show several model cards and a few from each game catagory the software is too wide range to cover everyone out just for XP compatible alone. Some games will simply run better on one make or the other by nature of software design. One example was older ATI AGP cards seeing problems when the Catalyst control center was running.
ATI is even giving out free games!!! if it is not intended for gaming? then for what? remember ATI have other cards not belong to the X generation that are for graphic workstations. if you only want to watch movies then any ati graphic card would do. again if you are a graphic designer or anything similiar to that ATI have different cards for those people.
if you would spend some time looking up the specification of x2600xt you would find the Memory Interface is 128-bit. just that already limited the card's ability to be one of the high end card.
if you would spend another minute of your time. look up all the cards that has 128bit memory interface. you would find that they all have a faster memory and clock speed than a 256bit memory interface cards. no matte how high the clock speeds are 256bit memory interface or higher is required for todays high definition gaming need. if you look at the nvidia 8 serie cards. all the high end cards have more than 256 or have 256bit memory interface.
and if you look at Entry-level GPU 8300, 8400 and Mid-Range GPU 8500, 8600. mid range have 128 memory interface and entry level have 64bit. again, no matter how fast your memory and chip clock speeds are. memory interface greatly limits your graphic card's processing speed
it is known that something didn't work out for the HD 2900XT. desgining errors? who knows. if you look at all older cards compare ati to ati and nvidia to nvidia. no 128bit interface is faster than 256bit interface from the same company. i am assuming by your saying a x1650 is faster than x1950 pro.
it is 128bit vs 256bit. just do a little research or even buy the cards yourself. you will see x1950 is faster than x1650. yes x1650 has faster memory clock speed and chip clock speed. there is a reason why x1650 is not consider as high end cards.
if you would do some research on google. i am sure it you will not find any review saying that HD 2600XT is faster than HD 2900XT
you are getting outdated news. first DX10 game is already out long time ago. it is called Company of heroes and your HD 2600xt is slower than HD 2900xt and 8800gts. no reviews will tell you HD 2600XT is faster than those cards.
tell me, when was the last time you seen a mid range card that is faster than the high end card.
from my experience ... NEVER....