Does a SSD make sense in a low-end PC?

I think it is a wonderful idea.

I use one in my backup pc which uses a G6950 cpu, and it makes all the difference in the world.

makes more sense than budgetting the $100 towards upgrading the cpu... Zippiness is all around disk i/o.

The point in which ssd makes sense is where someone wants a new computer and can budget the extra $100 or so to have an OS/programs drive. Even just that with 2 HDDs will add zippiness.

If you keep secondguessing yourself and go along this path of reasoning, a computer from 15years ago already does what you want it to do.

Absolutely. After installing my first SSD about a year ago, my opinion is I would never own a PC without one again, period, no matter what it was used for. They simply make that big a difference over a standard drive for delivering that "snap" just clicking around doing everyday things, boot up, and program installs. Worth every penny IMHO.

Three thumbs-up then ... a few more questions ...

1) Is using an SSD for the OS better than using a SSD for caching the HD (I'm thinking the new mobos that support SRT)?

2) Will I get the benefit of an SSD if I only put the OS on it or do I need all programs on it? I was thinking a 60GB SSD for OS only and likely would need a 120GB SSD for OS and programs (Office and WinAmp and not much else).

3) While the SSD is different technology I'm really just building a PC with two drives (C: and D: ) right? So I can load programs on the regular drive if I use them infrequently or don't have room?

1) yes. You can play around with srt but in practical use you maybe splitting hairs on much more complexity for diminishing gains. See my answer to (3)

2) you get benefits from whatever you put on it, so yes programs benefit, but how many dang programs do you have, and how much $ are you really saving between going from 60-128gb on a desktop, considering the overhead cost for the rest of your computer. If you are stuck with the exorbitant upcharge in pre-built laptops (like $400+ for $100 of hardware) though that's when you start to reconsider if it is worth it to get larger ssds. At today's prices you should at least the 128gb so it's a moot point.

3) yep. Usually you separate it as os+apps on ssd; then data is your second drive. Realistically people were doing well with 20gb hdds, until music, movies (aka data) really came into play. Typically there is less practical benefit in speeding up this data, it doesn't effect the snappiness of the computer in personal use.
Why are your apps so poorly built that they are multi-gigabytes in size. I suppose if they are games, yes when you're done with them but still want it, you can say just delete it or reinstall on slower data drive for apps that you can wait the "regular"
speed to load or work with.

There is a benchmark article about this jrau. I think there was a breaking point around the celeron / core duo area. Older cpu/ram combos are not limited by newer hdds much.

imho building a low end computer would be better with a 'new' mobo/cpu/ram as everything else is easily upgradeable from there.

The difficulty is that unless you can find cheap used hardware (I just sold my q6600 rig without video for $200). It is expensive to build a 'new' computer with 'old' parts. Not much more expensive to build a new one. Here are some prices... in Canadian $ more or less equal to US $

Gigabyte H77M-D3H $92.99 (can go H61 chipset for $65ish)
Intel G620 sandybridge $80
DDR3 1x4GB 1600mhz $25

Basic intel igp included $198

Hard to beat that with a stick. Now grab a cheap ssd and watch her fly. Upgrade ability all over the place to boot.