you shouldnt play games with mounted image's u should load the iso image's with pcsx2. anything u run in your pc uses cpu (and whatever u do if u dont close them down they will keep doing it! readyboost or anything else cant help here). if u check for updates regularly means u must have the bebruary updates if i am correct. are u sure u are using beta r1888 and march plugins from this forum or from official site? and yes your gpu and cpu are slow and u should run games in native resolution using lots of speedhacks

also i would recommend delete your pcsx2 folder (keep memcards bios and patches (if u have edit any of these) and do a fresh install of the emulator and plugins according to the instructions of the .txt file.
edit: there is no need to readyboost a whole hdd it doesnt do anything after 8-16gb and generally it doesnt give a speedup u can feel (also using an hdd for readyboost doesnt really work cause u need the speed of a flash stick or a fast ssd in reading/writing small files) (it doesnt do anything with pcsx2 at all!)
dxdiag mentions the directX u can use but that doesnt mean u use it cause i dont think your gpu can use dx11, maybe dx10.
also the more programs u run the more u use your cpu and your ram (the real ram u got on your mobo that is faster than any hdd....
the aprox. total memory also can be wrong cause in mine it says 2808 and i have 1gb card. so it doesnt say what we need to know...
more edit...: from the ddi version i can see u have directX 9 gpu (that's what it is i think...) and i see u have to update your gpu drivers 2 years....
and yep more edit: gamebooster doesnt seem that good to use program for me cause it closes windows processes that windows is running them for a reason and also pcsx2 is not a regular game so that program maybe close something pcsx2 needs.
If u want to check your whole computer specs use everest ultimate it has all the info there more than what anyone can understand or use.
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OS: Win 7 Ultimate x64 sp1, MoBo: Asus P5QD Turbo, CPU: Q6600 @ 3,0Ghz, RAM: Trancend 2x2gb 6-6-6-18 800 MHz, GPU: HD 4850 1gb.
Pcsx2: Always Latest