The i7 is generally the superior one, specially gaming-wise, though in some cases the phenom would outperform it, though not by much,(server).
You also have to consider the big price difference, I think the 1100t would be a better value for what you're looking for, in applications that can't take advantage of more than 4 cores though the i7 would be faster.
I'd just get a 990fx AM3+ mobo and one of the cheaper phenoms which will serve well, then when bulldozer comes out you can upgrade it easily. Intel will most likely change sockets in 2012 anyway.
Also I highly recommend an SSD, it'll make everything open much faster and improve your multitasking alot, you may find a good SSD + phenomx4 is all you need for now.
most applications are not coded for 6 core cpus, not even 4 core cpus.....all you really need for now is a dual core....4 cores is for future proof....until software companies start coding for 4+ cores it's not worth the price....
Lolz... Coded for 2 cores? yea right!
the OP wants to multi-task, so the more programs he runs, the more cores get stressed!
for example, take the case of a video converter(Xilisoft), when converting a single cip only 2 cores are stressed, but when you convert 2 clips together, all 4 cores get stressed. (You can watch it in task manager/within Xilisoft itself)
Basically, Video/Audio rendering and Games will take advantage of 4 cores. However 6 cores or an i7-2600 is realy an overkill unless u do loads of video/audio editing and rendering... or u use programs that will make use of 6 or more cores!
I am using an i3-2100 dual core hyper threaded to 4 cores..and got to say even 4 virtual cores(2 real + 2 virtual) Rawk...