Unless your nvidia card is an 8000 series or newer, there is no reason to update beyond the 169.12 driver.
Nvidia does not fix any issues with older cards and they do not tweek the drivers for better performance. They do triage at best on the newer cards only. So, looks like it's GTX only now. The 8000 series will definitely not see any driver improvements. Likely the same deal with the high end 9000 series, only the el cheapo entry level card support on 9200, 9300, 9400 type cards.
I have no comment on ati windoze drivers. I will say the propriatary Linux driver is better than it was, which isn't really saying much. The recent Linux open source drivers only support really old ati cards, for example, FC7 + X1900XT = no X. The 700 series is supported but I have had issues with some 800 series cards. So, ati still has a bad rep with many Linux users. Again, triage mode, focus on the market where the money is.
Neither nvidia or ati make money unless folks buy new cards, so, not really much motivation to extend older video card useful lifetimes.