Is the budget 800 per machine? or 800 total for a laptop and workstation upgrades? Or are you thinking a new workstation and upgrades to the existing workstation?
budgetwise, buying a new laptop with adequate specifications and upgradeing that workstation you listed aren't happining. Building a new one and upgrading the existing one is theoretically doable, but the new build is going to eat most of the budget. Technologywise, now is a good time to upgrade. Anything that was close to ready got released for christmas, so the new video cards and processors likely won't be out in general until the June-July timeframe.
I tend to prefer Intel processors over the AMD line, and i agree that the I-5 socket 1155 processors are probably the way to go. Video card, I hate ATI Radeon drivers. Hardwarewise I have no complaints on the cards themselves, and since AMD bought ATI, they actually work better with AMD processors. I always stick with nvidia though. No problems there,
I'm going to go ahead and assume that you are looking to build her a new PC rather than buy a laptop. With that in mind, Photoshop wants the following: Ram, More Ram, as many processor cores as you can throw at it, as much video ram (but not necessarily horsepower) as you can throw at it, and a secondary drive to use as a "scratch" drive to speed up rendering and any processes. With that in mind, this is what I would put together as a start:
Case: Cooler master Cm690 II - Currently on sale for $69 after rebate
Notes: Big, roomy, toolless, no issues with nosie or ventallation
Motherboard: At a minimum an Asus P8B75-M socket 1155 motherboard. $79
notes: only supports one video card, but has 4 ram slots, sata 6 GB/ sec and USB 3.0 More money spent here on an upgraded board with better controllers though wouldn't be a bad investment. The next revision up in terms of components and features start at about $130
Processor: Intel I5 3350P socket 1155 processor $179
Notes: Quad core, 3.1ish GHz, low wattage so low heat output. An I7 upgrade over this one would give you the hyperthreading cores for 8 logical cores total, but the I7's start at $289 for the I7 3770
Ram: 16GB Corsair (2x8GB) $65
Notes: ram is still dirt cheap at the moment. get one set of thsoe to bring her to 16Gb, and a dd a second to fill in the other two ram slots as budget allows. $65 price is after the coupon code EMCXVXW79 which ends on the 7th of February.
PSU: Antec 620W PSU $69
$392 without the drives or the video card (or the OS) at this point
OS Drive: Samsung 840 250 GB SSD $179
Data drive: 2x Western digital 500GB in raid 1 mirror $50 each, $100
Which puts you at $671 without the video card or OS. I would reccommend at that point pulling your 460 GTX, installign that in her new computer and using the remaining $130 to get one of these:
EVGA 650GTX 2GB $129 after rebate
Notes: Fast, lots of ram, Does NOT support SLI mode though.
I realize that doesn't include the $130 per license Windows 7 OS. i suppose you could drop the data drives or go with a smaller / non SSD, but the 840's are completely, unequivically worth it. they are damned speedy! also having dual 500GB data drives with redundancy gives her room to play with larger photoshop file sizes, but also ensures that a single drive failure won't lose all your data. I don't build anything these days without a redundant drive array in it somewhere. Drives are too inexpensive not to.
The video card would be a major upgrade for your computer. I'd also look at throwing some ram at it at some point. High end AMD CPU and board upgrade would run you $320-ish. You're basically equivelent to a high end I5 at the moment. Case and PSU are fine for the duration. Might want a bigger PSU if you ever decide to go SLI or Crossfire multiple video cards. No issues with your SSD, though you probably are going to want a bigger one eventually given how much room windows 7 takes. it sounds like you already know about the space issue though. I find that my 256 GB samsung 840Pro SSD is fine for my space needs, even with the multitude of games and utilities I have on here. If you have another $800 to throw at your computer though, I'd probably go with the video card (or maybe a higher end one) and the ram. after that it becomes a toss up between the CPU / motherboard or the bigger SSD. the bigger SSD isn't going to give you a huge performance boost over your existing one, but it would allow for growth for the next 3 years or so at least. Motherboard and processor I would almost leave alone unless you wanted to go with something really super high end because otherwise you would be looking at maybe a 10-15% improvement over what you already have.