I haven't heard a computer speaker set that I liked very much. I think you'd be better off buying a pair of good bookshelf speakers and powering them with a used receiver. If you have a two channel receiver around the house, that would work. If not, check Craigslist, garage sales, thrift shops, junk stores, and eBay. You'll find one, cheap.
Receivers have a lot of side benefits. Some of them make very good headphone amps. All of them have an AM/FM tuner and most of them have a phono preamp if you want to give vinyl a spin.
As for speakers, I think the Best Buy Insignia bookshelves are pretty good, especially for $88. You can find them here:
Insignia® : Bookshelf Speakers - BestBuy
These have something of an audiophile cult following. You can find mods, crossover replacements and other tweaks to get the most out of them.
I also think the PSB Alpha B1 is a terrific speaker. You can find the
Stereophile review here:
Stereophile: PSB Alpha B1 loudspeaker Actually, I just bought a pair this morning as a Christmas gift for my mother. They list at $279, but you can get them here for $169:
https://dmc-electronics.com/Default.htm
I drove down there and picked them up at the store. David, the owner, is a nice guy and helpful. I'd do business with him again.
There are other quality bookshelves out there, but these two will outperform pretty much any computer setup on the market, even ones that cost far more.
Watts don't tell you everything about a pair of speakers or a receiver. It's sort of like trying to figure out how fast a car is by only looking at the horsepower. A 500HP engine sounds powerful, but if you put that in an eight ton bus, it's going to creep along. A 200HP engine in a Lotus would scream past it. Likewise, if you use a very efficient speaker, like one of Klipsch's horns or a Lowther, you can get earbleeding sound with two or three watts. Even a 1.5W amp will make them uncomfortably loud. On the other end, you could have something like an Apogee ribbon with a 1.2 Ohm impedance that will make a 100W amp melt down. Pick the speakers you want, then find an amp capable of driving them.
If you want to do some homework on receivers, look here:
www.fmtunerinfo.com. They provide a lot of good evaluations and you can figure out what brands to look for. Personally, I like the older gear from NAD and Marantz, but there are other good brands, too.