Continue replacing PSU or ditch box?

[SscoootzZ]

I have a fairly stock Sony VAIO, circa 2005. I've only made low-level changes by adding RAM; I think I'm maxxed out @ 2GB. I'm currently running WIN7 Pro 32-bit. The PC is basically a daily driver and, though it stands ready for replacement, I'll likely re-purpose it as a streaming device using XBMC and running a simple dual-boot with a light, media-server Linux distro. My issue is one of financial logistics because I've replaced the PSU twice since the OEM unit failed. I believe the stock PSU was 230W; the next PSU was 450W, and the final was 650W. I'm seriously puzzled as to why I've had to replace the PSU so many times, even though the PC is 6 yrs old. I'm honestly unsure whether to keep pegging it along at roughly $50 a pop, or to dismantle the usable devices and move on completely. Any insight and experience to help me make this decision is greatly appreciated, in advance. Namasté, ~:sDs:~

[Bartolomeo]

This is really a very weird problem and it will be better for you to call some specialist and he can handle the thing better by testing the system.