Fermenting temp. and attenuation...

Hey. I was looking up yeast info, and started wondering... My (first) batch is fermenting nicely with a good yeast cake at the bottom, etc. The yeast I'm using has an optimal temp range of 67-74. During the first day or so it fermented at 72-74, but it has slowed since and the temp has dropped to 68-70. So my question is...Does the fermentation temperature (either primary, or secondary conditioning) affect the potential alcohol and attenuation of the yeast? I know it's only a few degrees, but I was just curious.
Thanks,
Btw, thanks to everyone for their quick and helpful responses. This forum, along with research has (I think) made my first batch a successful one. Even though it has about a month to go, it started fermenting in about 5 hrs (with my yeast starter), which is great from what I can tell.

What was the temp when you first pitched? 72-74 is a little high and you may get some fruity esters in your beer. Yeast generally don't like big temp swings, usually a degree or two is fine. The yeast can go dormant if the temp drops too much, but if you are at 68 you should be fine. I like to pitch a little cooler like 66 and let the yeast warm up to 68 and I try to hold it there for at least 10-14 days, then I might let it creep up to 70, I use a lot of WL 001 Cal Ale and that is optimal for that yeast. The key is to not rack it off too quickly, let the yeast do their job.

Eastside

When I pitched the yeast starter was close to 72, and the wort was probably 68-70, it was hard to get an accurate reading on the wort, but it was definitely below 72. I'm not sure, but I might "want" esters in my beer. I'm making an english old ale, so diacetyl (if that's what you mean) wouldn't bother me, but will higher temps produce off flavors? (as in..bad?)

btw, will lower ale fermentation temps produce "smoother" beers? I plan on racking to secondary after 8-14 days and keeping it much cooler (63-68 degrees) for maturation. is that ok or should the entire fermentation temp be a bit lower, closer to 70?