No, not the best time, but then do we sit on the need just because fall is the best time. If the lawn needs fixing, then who would say 'well, I'll wait until October and not look at it all summer'.

Often it only takes minor fix-ups to start the lawn fixing itself. Raking the debris off, opening up furrows so the grass seed can find a place where rains won't wash it away.
But, seeding does come down to 'when' is the best time as far as time of season. The soil has to welcome the seed for good germination so as temperatures begin to rise it will affect how soil temperatures rise. The temperature of soil is usually regarded as a must to be above 55� or the seed will just sit, waiting for the optimum time to begin. But then again, that's not a bad thing to do...the seed will just wait and germinate the their time is right.
It does though allow birds to feast.

We use the interval between when its not the optimum time to get the ground ready to accept the seed.
Raking, rolling if necessary, spreading a little topsoil or otherwsie make the soil want to welcome the seed.

If it is not too big of an area you might consider sod

i did spring seeding last spring after our home was built. most of the forum members were not suggesting it but i had to have lawn by end of june to keep bldg department happy. i followed all the suggestions i got here and had pretty nice lawn by mid summer. just make sure you get quality seed, have water schedule and follow all the suggestions you get here. i germinated quite a few weeds too, so every weekend me and my wife would hand pull them. as the grass got thicker the weeds retreated. now after one year i have only few thin spots which will hopefully fill in this season. i seeded kgb. here are some images of my lawn
http://forums2.gardenweb.com/forums/load/lawns/msg0917544522612.html

VERY NICE!!! But let's make sure we get the correct story here. Did you accomplish this with your wife's help, or did your wife accomplish this with your help????? Lol.

Either way, very nice result. As evidenced, spring seeding can yield a positive result.

the truth is, my wife pulled some weeds and gave up, complaining about damn crap grass. i couldnt stop laughing.

I think I have missed my opportunity to overseed this fall but plan to do it in the spring by pulling my core aerator over the lawn multiple times, then dethatching to loosen up the surface followed by broadcast and drop spreading seed. However, I have a real crabgrass problem each year. How can I sow new grass as well as prevent crabgrass - surely both need to go down around the same time and the crabgrass preventer (I use Scotts with halts) will also stop the grass seed from germinating.

Any suggestions ?

You can sow grass seeds and Use Tenacity at the same time. google Tenacity.

Unfortunately I have close to half an acre....Tenacity would break the bank. Any other suggestions ?
I'm thinking more about getting the timing right. Can I put seed down then wait a couple of weeks before putting crabgrass preventer down or should I have just seeded this year ?