Vista - Just installed - NO Internet & VERY Slow!

I just did a clean install from XP to Vista ultimate 64 because I upgraded from 2gb ram to 6gb because I finally ran into a game that needed more ram.

Anyway, I've reset my modem, restarted, set up the connection (broadband), set it to detect setting automatically, went thru all the vista diagnostic suggestions... and still no internet. I'm using my Win7 hard drive at the moment. (never had Vista before)

Worse than this though, is Vista is Extremely slow. It freezes every 5 seconds for 10 seconds and takes forever to try to do anything at All !! its getting very frustrating.

I can't update any of my drivers because I can't connect to the internet !

Would Greatly Appreciate any help!!
Thanks!

I would redo the clean install.

Ok I reinstalled. And that seemed to fix it for a short while.... I was able to get internet and the lag time wasn't quite as frustrating... The internet quit working on me though and now my computer is back to lagging terribly. It's Very frustrating.

I have 6gb of RAM and a 2.4ghz dual core processor. the memory usage doesn't exceed 15% and the CPU usage goes sporadically between 0 and 50%. Even when its at 0% the lag is still the same. little pop up windows told me a couple drivers had been installed when I had the internet for a short time, but I don't which ones. I tried to go online to update my mobo, video, sound, Vista... but couldn't get online.

update: I downloaded the ASUS chipset, nvidia and creative drivers from this OS (w7) and installed the video and sound drivers.. but Vista tells me the mobo chipset I dl'd from ASUS (Chipset_Vista_V51026000813) doesn't work for the OS...??!! that WAS the specific chipset for 64bit Vista! There were BIOS versions I could have dl'd but I don't really know anything about that.... should I dl those as well?

Its still very slow and the internet connectivity varies. Sometime I can get it to connect from "my computer-----Network---X---- [but not to the] Internet" if you can picture what I mean.. I even had it green for both and still couldn't access a web page (but programs could access the net). but usually there's an X between both-- and it's getting ridiculous.

Should I try another install, I'm about fed up. I have a lot of work to do and I can't keep reinstalling vista. Might there be any other solutions? Please Help
Thanks

Update: Long story short: I uninstalled vista and installed windows7 and ran into the same problem! reinstalled. deleted and recreated the partition and reinstalled (64bit).
I don't know what the heck is going on... because I'm using windows 7 (32bit) as I'm typing this... I checked all the settings on this OS and made sure they were the same on my other one... and it still doesnt' want to work.

I've reset the LAN adapter and "investigated modem issues", along with rebooting modem and pc MANY times. sometimes the connection will make it to the "network" but not the internet for whatever reason, but usually it doesn't even connect to the network, even though it knows that I'm connected to a network...
*when it connects to the network, it says its an "Unidentified network".

* I finally got it to spit out the cause ::
"LAN doesn't have a valid IP Config"

PLEASE tell me how I can fix this. I have the internet options set to detect settings automatically, and not trying to dial anything.... What else can I do??

(**the lag part is fixed though!) But I'm close to my wits end with this problem and would GREATLY appreciate some help