Mac Noob eMac question!

Hi guys,
I got an eMac yesterday from work for a bargain £5! (1.25mhz/256MB Ram/40GB HD/Combo Drive), it works fine, but I have a few questions relating to upgrading it before I really start to play around.

I have burnt a Mac format image using my PC via TransMac onto a Verbatim DVD+R DL disc. under TransMac this shows the same contents on the physical disc as the image, but when I insert it into my eMac, it just ejects the drive immediately - any ideas? I am assuming the combo drive might not be compatible -it is at Rev 2.05 if I just need a firmware update- or would I need to get a super drive and install that instead?

If I do go the super drive route, would it be best to install a new HD at the same time with the case apart? Is there a maximum HD size, or can I use any brand/size 3.5in IDE drive (this way I could keep the current 40GB drive as-is, without formatting anything).

I also plan to upgrade the ram, as it is so cheap these days, does the Mac use PC2700 DDR333 HD, or non HD sticks?

Hopefully someone can help me out!
Cheers,
Paul

Firstly here are the specs for your eMac which can handle 2x1GB modules of PC2700 DDR SDRAM:-

http://eshop.macsales.com/Descriptions/specs/Framework.cfm?page=emacearly2004.html

Go and buy Tiger OS X.4 in the full retail install DVD version, a black disc and not a grey system update disc which are machine specific. You will need the install DVD to repair the HDD, do a format and then to install the OS.

Most top brands of hard drives, Seagate, Maxtor, WD, IDE 3.5" will be just fine in the eMac, but remember these drives will not be formatted to Mac OS Extended (Journalled) and again you do need the Tiger install disc.

Suggest a minimum of 1GB memory for Tioger and 2GB for Leopard if you want to go that far.