That system, if real, represents a metric craptonne of bang for the buck. We're talking about "sounds too good to be true" territory -- not that it is too good to be true, necessarily, but there's some grain-of-salt stuff to go over.
The first thing to notice is that the lights are rated at "250W". That's 250 Watts. The guide numbers they state (45 in feet at ISO 100 without a reflector) fall in line with what you'd expect for a monolight rated at 100-150 Watt-seconds (joules). There is a chance that they are merely using very inefficient flash tubes, but it's a lot more probable that the rating means exactly what it says: the lights draw 250W while recycling (180W or so of recycling power, plus 70W for the modelling lamp). For comparison purposes, I had a couple of Elinchrom 250RS monolights a few years ago that had a true 250 Ws (joule) flash power, and I could only use one of them on any given household circuit -- they drew nearly 1800 watts while recyling (they could recycle to full power in just under half a second). They also had a bare-bulb guide number closer to 100+; I can't recall using them at anywhere near full power except in a large softbox or reflected from a full sheet of foamcore at my usual shooting apertures (they saw most of their use as auxilliary lights, though -- I tended to use the 500 and 1000 units for main lights).
So maybe you don't need a true 250Ws, and these will do just fine in terms of their actual output. Now consider that they're giving you three lights and throwing in two softboxes, two umbrellas, three stands, barndoors, gels, a case and a wireless trigger for that price. That gets my Spider-sense tingling. Okay, we'll accept that anything with the word "photographic" in the product name is going to come with a bit of a mark-up, but there's a point where you really have to start wondering how much can be saved in materials and labor without compromising the product. Are the lights electrically safe? (Is the CE sticker real?) Can the stands actually support the lights when extended? Do the lights stay at the angle you set them? Do the barn doors stay where you put them? Can you adjust the barn doors without ripping them off the frame? What about the softboxes and umbrellas -- do you really want the equivalent of a dollar-store bumberchute? How reliable can the wireless trigger be?
Don't take that as a "don't buy it" directive -- it's just stuff to carefully look at right away if you do decide to buy it. Take a good look at the vendor's return policy in any case. You never know, this could be one of those rare real bargoons in life, but you want to be covered in case it isn't.
As for the original question, a GN of 45 tells me that you want the higher-power version of the lights. They'll give you f/5.6-8 for most real-world shoots at max power and at a distance where the softeners actuall soften. (A softbox only gives soft light when set close to the subject -- within twice the diagonal at the most. Beyond that distance, the highlights start to become specular, like you'd get from a normal hard reflector up close.) You can always turn a light down for a wider aperture, but it's really hard to turn it up past the max if the light needs to be further away than 4-5 feet or you need more depth of field.
