Again apologies for not be able to check, hope you understand from email.
If you are looking at new PSU then no need to spend more than £30
Without listing the computer specs, I'd hazard a guess you'd need no more than 350W type.
I'd guess the following would suit your needs:
Antec Basic 350W
If you want a guide to installing the PSU then read on:
PSUs are held in place by (on the case in front of me) by 4 screws, i.e as shown here:
Turn off the power and remove the side panel. Trace all connections from the PSU and gently pull the molexs:
from the back of the cd-drive and hard drive.
The 2 cables to the mainboard (ATX power connector & P4 12v power connector - see below for links) may have a little plastic tab thingy which needs to be pushed against the connector before removal.
Once that's done you can remove the screws and the PSU should slide 'out' of the computer - whilst holding the underneath of the PSU with one hand, use the other to slide the PSU further into the case. Eventually it should come out.
To install the new one do the reverse, starting by screwing the new one into place 1st.
You'll have wires going to various components (cd drive, hard drive) etc. these basically on fit one way round and push in/pull out.
There'll be 2 other connectors like this:
ATX power connector and this:
P4 12v power connector that will need to be connected to the motherboard also. The longer one usually has a clip thingy that prevents you from inserting the wrong way, (think it only fits one way anyhow), the square 12v connector will only fit one way.
The floppy connector:
Floppy drive power connector does fit both ways round
however should be fitted correctly else damage may occur!! As haven't fitted one for a while I can't remember which way round it's. Hope someone can post saying this???
Hopefully haven't put you off doing this as it's kind of hard to explain without going long winded (i.e. what i've written

). It isn't as hard as what it may seem from the text. Even someone with no experience can do this in less than an hour I'd say (well we all started somewhere

)
*edit* not sure of your case type, whether it's mAtx or Atx. No previous experience with e-machines so can't definitely say what cases they use.
Should think that the PSU I've listed would fit though.
*edit 2* Sorry for the lack of pictures, I was doing this late at night. Also if there are any mistakes in there.