EasyBCD looks interesting so I'll d/l for future use.
In the meantime, I was able to get around the issue by disconnecting my hd0 (with Linux, XP, and Grub 2); since my hd1 (which has Windows 7 in it) was in itself bootable, I just booted off that. With no Grub 2 intervention, Windows 7 exhibited normal behavior and I could see the Advanced Boot options and make my tweaks since the only OS showing was Windows 7.
I had concerns though - will re-enabling the Grub 2 bootloader skip over my new Windows 7 boot parameters?
So, I gave it a go. Reconnected hd0 and picked Windows 7 from the Grub 2 list. When Windows 7 kicked in, I checked msconfig. The Boot settings now showed "Selective" instead of "Normal." Therefore, my tweaks are in effect even though Windows 7 was again NOT showing on the drop down OS list.
And ... my Hauppauge PVR 150 now works great!
I am happy. Only drawback is that this solution will only last as long as I decide to stay at 4GB RAM. Oh well, I'll be upgrading hardware in about a year anyway so I'll probably buy a new TV card.
But my heartfelt thanks to all of you for your helpful suggestions and insights. Crisis managed.
Next step is to bring this behavior to the Grub 2 forums in Ubuntu land.