Vista Biz 32 or 64 - or bump to Win7 32 or 64?

[brettmansdorf]

Have X200T - SL9400 (1.86) + 4G. COA is for Vista (32) Business.
Question is...

Does anyone have a firm understanding of the benefits of the 64bit OS, and what might be the 'gain' if I upgrade to either Vista 64 or Win 7 64?

The majority of my 'stuff' is large inter-twined excel spreadsheets (100k line/5-10 tabs/xref'd to others on HDD).
Lots of Acrobat conversions and editing (pro)
Occassional Adobe image manipulation (AI, PhotoShop, Lightroom)
Always with MediaMonkey playing (classical/jazz) in the background.

I know most of Adobe's stuff is set for 64 bit, but is the gain significant. I'm unsure on the excel stuff (no matter what PC I'm using, they 'churn' a bit).

I am a bit reserved to upgrade - as I hate loosing the recovery partition on the HDD - simply as a security blanket.

I'm on the god awful 5400 -160gb hdd - which will get up'd anyway. Will an SSD show significant performance gain for the above programs or just stick with 7200rpm?

Thanx!