Lochardil

Hi All, I have a three and a half year old HP Desktop. It's spec is below. It's actually running Ubuntu 12.04, not Windows. I have a very limited amount of time to fix PC issues these days, due to spending most of my time looking after my children. I'm trying to weigh up whether just to sell this for spares or repair, or to try to fix it. Here's the issue. Sometimes when I switch it on, the monitor acts like it's not there. No communication between them at all. I also use the same monitor with my work laptop, and it works fine with that. Other times I get a completely frozen image, I can only hit "power", then when I power the PC back on, the monitor acts as if the desktop is not there again. It's connected through a HDMI cable. Oddly enough, there's an old style VGA socket on the back of the HP desktop too (it does not look as if it's also on the Graphics card, as it's on another part of the back of the PC). I tried plugging the monitor in vga to vga, but same behaviour. When I fire up the HP desktop, the monitor does not even display the HP BIOS, so that's why I'm assuming this is a hardware, not an operating system issue. So here are my questions: Does it sound like a Graphics card issue? If so, what's the cheapest graphics card I can get away with, within reason (bearing in mind this Pc is only ever used for web work like Google Docs). This is a long shot - but I do have a very old Pentuim 3 PC tower system from 2000 I can cannibalise. It's been so long though since I plugged expansion cards into PC's I'm sure the card that's in this system won't be compatible? How easy is it to swap a graphics card out? Thanks, Tom.