I'm guessing the mobo ya refer to is the Epox 8KHA+.. which is pretty good about fitting any type of heatsink. Generally, 60mm heatsinks that cool nicely tend to need loud fans, and 80mm heatsinks can do the same job but with a slower fan, since the fan being placed on it is larger. 80mm heatsinks generally cost a little more than 60mm's and in some cases are tougher to install though, and may not fit on all motherboards. It's really up to personal preference and what your motherboard allows. If you have the Epox 8KHA+, you can fit basically any popular heatsink on it. A popular 60mm heatsink is the Thermalright SK-6, and a popular 80mm heatsink is the Alpha PAL8035.
If you're doing your first PC and not planning on overclocking, I'd go with the retail AMD heatsink. It's reliable, doesn't keep the CPU icy, but keeps it within spec, and using it along with a boxed Athlon processor gives ya a 3 year warranty.
So all in all I'd recommend Alpha, Swiftech, or Thermalright for your heatsink solutions. If you're looking for fast, cool fans I'd go for Sunon brand (Delta is even moreso, if you can stand the high pitched whining), and if you're looking for silence I'd suggest Panaflo fans. Keep in mind though, that if overclocking isn't your goal, the stock fan that comes with the Athlon would be great. Or, if you bought the Athlon OEM, then take a look at the low end Coolermaster heatsinks - same thing as the ones that come boxed.