Thank you both, Veritable Quandry and Ms. Alter, for your helpful advice regarding a laptop capable of giving me more of what I want from Second Life, without costing an arm and a leg! I followed your suggestions, trying to determine what combination of features would actually be useful and what would be overkill given the server-side and other constraints that are just facts of our Second Life.
Although I had my heart set on an HP Pavillion dv6t or dv7t in January, it was obvious by late Feb that the better choice for me would be one of these three: Lenovo Y550P, Fujitsu NHLifebook, or Toshiba X505-Q860 Qosmio. I contemplated an HP Envy-1150NR (despite embarassing name!) because of the i7 processor, metal alloy frame, and www.notebookreview.net assessment of it's "Class 1" graphics card. However, the card is ATI, either 5830 or 5850, and I was hesitant after reading comments about reliability etc. Slight aside, but I wonder if some of the ATI graphics cards are more suited to high-end business users, whereas the nVIDIAs seem to do better with gaming applications? However, HP Envy was very expensive, even entry-level.
So I didn't go down the HP path, but nearly went with Lenovo. Ideapad Y550P had some nice features at a good price point, including a spill-proof keyboard, sub-woofer, i7-720 processor w/ 6GB of DDR3 and nVIDIA GT 240M graphics card w/512MB dedicated memory. Unfortunately, there wasn't anywhere I could try out a floor display before ordering. Point became moot upon realizing that the model of interest was suddenly discontinued and pulled from shelves everywhere on the day before I was ready to buy!
The Fujitsu and Toshiba have similar specs. Because of my prior familiarity with Toshiba plus scarcity of Fujitsu products in my homeland, I bought a Toshiba Q860 last Saturday. So far, so good! No problems running Windows 7 in Second Life, and no software issues with 64 bit. This is a lower-end Qosmio, with an i5-430 processor (I couldn't afford the i7), dual-core with 4GB DDR3 (2 Dimm), a fast 500GB drive, and a decent graphics card: nVIDIA 360M with 1GB of DDR5 memory.
After reading your suggestions (saw similar elsewhere once I knew to pay attention), regarding Second Life's disinclination to fully utilize two graphics cards, a single GPU generates quite enough heat, thank you! However, my DIY approach was to elevate the new laptop using six stoneware coasters, all on a stone, tile or wood surface, and the air seems to circulates okay. Similar thoughts about underutilizing power of hyper-threading from an i7-720 (or whatever follows 600). My new laptop is very large and heavy (18.4" screen, maybe 10lbs?) but I'm fine with that, as I'm using it as a desktop replacement. And the 16:9 ratio display is wonderful with my impaired vision. I was a bit concerned about high resolution screens with very small fonts, or so I'd heard, but I've adjusted the settings for my needs. Works great for other apps too! Maybe I can finally get SAS or SPSS to run decently on a home PC now....
I really appreciate the effort and care taken in responding to my question, particularly since it gets asked over and over again on these forums. Your input was immensely helpful to me. Thanks again to both of you! ;@)