the gt420 got its info leaked, no idea when its going to release. its 5.7in (14.5cm) long and 2.7in (5.8cm) wide and consumes up to 50w. not sure if its as good as the 5570. http://www.hexus.net/content/item.php?item=26347
edit-just found out theres a low profile gts450 by palit. should be the best low profile card since the gts450 is better then the 5750. http://www.newegg.com/Product/Product.aspx?Item=N82E16814261078&cm_re=GTS_450-_-14-261-078-_-Product
Thanks for the info, I searched for the gt 420 earlier in the week and though I found info on it I couldn't find physical dimensions, thanks. It's comparison to the 5570 is up for debate, but if it compares to the gt 240 (it has half the processors but they and the memory -all 2gb- are clocked slightly higher) even if it's a good deal less. It will compete with the 5570. Either way the gt240 will probably be the better deal.
As for that gts 450 I saw it earlier and got all excited, but then it turns out it's about .5 inches too long. Oh well (it also uses a little more power than I would like).
I think I'll just wait until a good card comes out, or just do the build and use the IGP until it does.