I am currently using Windows & Ultimate, 32-bit with 2GB of RAM. My system’s max RAM is 4GB. If I upgrade to Win7 Ultimate 64-bit, will I be able to install more than 4GB of RAM on my Lenovo T60p?
It depends on your motherboard, you need to check your motherboard specs what is the max. amount of RAM it supports. If it's a laptop, just search for it online on sites like Amazon and I am pretty sure you will find this info in the specs.
Moreover, you should know that Windows XP 32-bit can recognize at MAX. 4GBs of ram. So even if you have a motherboard that can support up to 8GB of ram you won't be able to utilize more than 4GBs under Windows XP 32-bit. The 64-bit version on the other hand can recognize up to 128 Gbs (might be wrong with this number). I suppose in this case the limitation is your motherboard.
My 32-bit system is 64-bit ready. So I can load up on the RAM?
Depends on the amount of RAM your motherboard can support.
From what I have read, if you have a video card with memory on it, that also effectively reduces the amount of system memory w7/32 can address since the total memory is limited to what can be addressed in 32bits. For me having 6gig has not done much. I have no programs that address huge amounts of memory. (not a gamer).