I'm using Lotus Notes 8.5 and Windows 7 at home (32 bit) and at work (64 bit).
I was thrilled to find today that the ability to 'Drag and Drop' files from an Outlook email or the desktop to a Notes document has started working again. I had Windows Vista before and that function didn't work at all. Actually as far as I can see it still doesn't work in Windows 7 64 bit, and neither does the Windows/Notes 'Single Sign On' work in 64 bit Widows 7, but it's certainly getting there.
Windows 7 32 bit and Notes client (Admin/Designer et al) in 8.5 is really very good indeed for my needs.
Windows 7 and Lotus Notes client