Mashed up computer... NEED HELP!

Ok, around three weeks ago, my computer was acting sluggishly and etc, and I switched it off whilst it was taking it's time to shutdown. This led to the problem that it restarted itself during boot up. Anyway, came back after a party in London, contacted HP and they sent a nice email offering suggestions. I had done a system restore and it claimed that the I830 (something like that) could not be found and hence, apparently, there was something wrong with the file and couldn't locate whatever. Now, to express my anger at the computer, I took it apart (better than putting an axe through it). Put it back together and now all I get are static lines on the monitor.

I need help... on both of these problems, more importantly, the latter as I can always reformat the system.

HP Pavilion t3250 series, 2006, XP, I dunno what other information you need.

Your PC starting up comes in 2 parts. Posting and booting. Posting is the black screen part that runs through the hardware parts, booting is the OS starting up. Now based on your description, the PC isn't posting. Which may mean you didn't put it back together right. Crack open the case and try and turn it on again. See if power is getting to CPU fan and the MB. If it is then check the RAM. See if it's inserted all the way. If you can get all the connections right and it still won't post, either a RAM stick or the CPU is dead. A PC should still post even if the HDD or video card aren't working.

Is there any way of seeing if I've got the connections right? Like a diagram or anything?

Nope. Best bet is go to your motherboard manufacture website and see via the instruction manual.