Big-Mike,
I'm not one to be disagreeable, so I'm not but I'm opinionated so hear me out. In your post I'm pretty sure you contradicted yourself: "...i will see,how v4 is running genrally, before i buy new hardware...".
V4 running "generally" with recommended hardware is going to be a good smooth experience, trying to run it off of a hard drive and not a solid state drive, well I'm guessing that will not be as smooth as with an SSD. The statistics bear it out. Also, I'm curious about what you mean by "running generally." Does that mean no addons, only stock scenery, ORBX or no ORBX, etc. If you install V4 stock with your rig and the HDD, then you may have an enjoyable experience...notice I said may. Please don't take this as some stranger being a jerk, I'm just trying to offer one perspective. When I went from FS9 to FSXA, I tried to make a system last over 5 years. It did pretty good considering the VAS limit and the bug ridden "game." Then P3D comes along right at the 5 year point.
I knew LM from my military days, and it made me smile when they basically started what is called in software engineering iterative or evolutionary releases. That is what made me save my money (I'm retired) and when it was the right time I spent the money. I saw that some folks use the HDD to store scenery, then use one SSD to run the OS, and one SSD for the sim. Personally I like to run my OS on a smaller SSD, and the sim and scenery and addons in a large SSD, but I only use a regular WD HDD as backup). I would like to add a third SSD just for the scenery.
It was all worth the cost, man was it worth the cost. And that cost can't be helped other than waiting to get a decent SSD or video card or some other part at as low a price as possible. There are always good deals. Also, I'm not telling you to run out and buy a entire new rig, install V4 on what you got with that HDD and see what the stats are (FPS, CPU and GPU stats, etc.). Then ask what people are getting on their rigs (and note the specs if they have them as a signature block). Then decide if you want to give up a new hunting rifle or whatever your luxury or sacrifice you want instead.
I hope this discussion is helpful and not a waste of your time. After flying for real, the simulator is my fix, so I guess I'm a junkie.