How to improve my pc?

First are you running Windows 7 32bit or 64bit?

With regards to memory, are you maxing out your memory? Your only running 4GB so if your gaming or doing image/video editing or 3D rendering you may be maxing out your RAM.

If you're running Windows 7 32bit, RAM wont matter since your maxed out at what it can address at 4GB. If your running 64bit, you can go up to the boards limit of 16GB pretty easily. According to your CPU-Z screen shots your using CM3X2G1600C9N memory which looks to be a Corsair DDR3 1600 Cas 9 1.5v memory. However I cant find that model actually listed anywhere. Mixing brands, speeds and timings is bad juju, so your not going to want to do that. So what you'd likely end up needing to do is completely swap out your memory for a new set of dual channel memory. G.Skill, Crucial and Corsair are the top 3 I'd recommend. You can pick up a dual channel set of 8GB (2x4Gb) DDR3 1600 Cas 9 1.5v memory for $70-$80. I like Crucial Ballistix but that's just my preference. Get two sets of 8GB (2x4GB) and you'll max out what your board can do.

To find out if your maxing out your memory, load up whatever program you want to use and look at your memory usage with system monitor. If your maxing it out, its time to upgrade your memory.

Also it could possibly be your hard drive. If its an old drive, it might just be time to put it to rest and get a new one. Especially if your using a IDE/PATA drive, which it looks like your board supports. You're board supports SATA drives so thats a super cheap fix, $70 will get you at least 1TB drive that will out perform your old drive if its as old as your CPU/Mobo. The only real difficulty will be cloning it all over if you don't have your data backed up and don't want to reload your OS. But there are a ton of utilities out there for that. A SSD drive will give you the biggest boot in drive performance but it'll cost a lot more than the traditional drives. You also wont be able to take full advantage of its speed since your using a max of SATA II, but it will help.

Now if your not hitting your RAM limit, or your HD isnt an issue, you may be hitting a bottle neck of having a first gen, 5 year old i5 CPU. I'm currently on a first gen i7 and am hitting that issue myself. Chances are your hitting that wall too. If that's case, you can upgrade your CPU and Motherboard to the current Haswell line (socket 1150). Bad news is, obviously, that's the most expensive options but that will net you a good performance increase. Good news is you can use your existing memory on the board. You can likely use all of your HD's (providing their SATA), video card, maybe even your PSU. Now since I have no idea where you can buy that same memory (as I mentioned before) if you intend on increasing your memory from the 4gigs, you'd be better off just chucking your existing memory rather than try and mix brands and timings.

Those would be top 3 ways to increase your performance if its hardware related.