I was just responding to leedz comment. To let him know there is at least one other difference between the 9000 Pro and 8500.
Comparing an 8500LE and 9000 PRO it gets a little fuzzy. Clock for clock the 8500 series outperforms a 9000 series. That's when both cards are clocked the same. For example, the the ATI retail versions of the both the full 8500 and 9000 Pro are clocked at 275 Mhz core/275 Mhz memory. Of these two, the 8500 performs better.
The retail version of the ATI 8500LE is a different story 250/250. To compare this to a retail ATI 9000 PRO is a little more complicated because of the Pro's 275/275 clocks. I've not seen any head to head comparisons between an 8500LE and 9000 Pro so I'm only guessing when I say that I think the retail 8500LE is still a little faster than the 9000 PRO despite the clock deficiency. Comparisons get worse when you start talkinga about the slower 8500LE's. Some of the OEMs are clocked at 230/230, 230/200, 250/200, and one is even 250/166 (yuck!).
As for the retail ATI 8500LE vs retail Gigabyte 8500LE, I don't know off hand. Check the clock speeds. I do know the retail ATI 8500LE is clocked at 250/250. I don't know the clocks of the Gigabyte card.
Other than the clock speeds check for features. The ATI version does not have a DVI port. The Gigabyte may have one but I'm not sure. If you need the capability of second monitor you need to check this. If you also wish the second monitor to be a CRT (vs a flat panel) you would need to check the card has a second RAMDAC which is needed for CRT support on the DVI-I connector.
You can avoid all the issues by purchasing a full, <b>retail</b>, ATI made (BBA) 8500 (not 8500LE). This gives you everything including TV-out (cable included), DVI-I with both flat panel and CRT support (not sure if a DVI-I to SVGA adapter is included), and the core and memory speeds are at 275/275.
Genuine ATI 8500 cards (both 8500LE and 8500) have been very good overclockers. You will often see people mentioning "BBA" meaning Built By ATI. These have been the best. I have an OEM 8500. Stock clock is 275/250 but I routinely overclock it to 300/325 (I need an extra cooling fan for this). I have clocked it as high as 308/340(680 DDR speeds!). This card has a DVI port but its not a DVI-I and does not support a second CRT.
I personally don't believe that the 64MB vs 128MB is enough of an issue for the usable life of the 8500. By the time large amounts of video memory become an issue you probably want something better anyway. On the otherhand, if there isn't much of cost difference then get the one with large memory but be aware that the 128MB 8500s usually are clocked a little lower than their 64MB counterparts.
<b>99% is great, unless you are talking about system stability</b>