hd help

Those 233s had an ATA-3 bus, so any Parallel (not serial) ATA drive will do (its really hard to find anything but ATA-6, but they're all backwards compatible).

top hit on google might be helpful.

Watch this page for good deals on Seagates (the only drive with the 5 year warranty).

Once the harddrive is replaced, boot the machine off your 1st Tiger CD*, partition the drive HFS+, and install the new system fresh. Put your old harddrive in a usb† box. Once you boot for the first time, it will ask if you want to transfer settings... if you want, you can transfer them from the usb box (assuming you were running OS X before... I don't know if it supports migration from OS 9 or below). After, transfer the rest of your files off the old drive (if there are any).

*Tiger came on DVD, I think... but you can get it on CD somehow, I think by sending it to Apple and requesting CDs... stop by an Apple store and ask if you can.

†usb enclosures are cheaper and more common, but firewire enclosures are faster... since its a 4gb drive, I wouldn't invest too much in it.

One more thing... find out if your iMac is firewire bootable with your upgrade... if it is, I'd put your NEW drive in the firewire enclosure, and install the system on that... then, when you are ready for a new computer, you'll already have your system portable, and migration will be breezy. Thought some more about it... depending on the fw upgrade itself, firewire will be considerably faster than ATA-3 (at least in all the tests I've run). Just something to consider.

Getting to the harddrive in those Rev.A iMacs is somewhat tricky. You might want to find a guide online somewhere that shows how, if there is such a site. There's a clip thing above the harddrive that keeps the CD drive primed and stuff like that. You're really pushing the limits of that old machine. I don't remember hearing anyone putting Tiger on one of those machines. It's got that old RageII video chip in there which would be pretty limiting. Putting a faster harddrive in will increase heat a little. I assume you've got a Sonnet Harmoni upgrade in the machine. Personally, I'd sell that Harmoni while you can still get a good price for it, and buy a newer computer--an eMac maybe. Of course, I don't know what your situation is. Your name makes me think you're in Italy.

yeah, ive got the sonnet, but i dont know how much i can get for it, and at the moment im living on no income but b-day money...
my friend just put tiger on a 1 gen calmshell ibook and that had 400mhz, so im not too worried, and if i fry this one i can always use the family cpu, which, god forbid, runs the windows........
not to mention that im already running 10.2, and i only want the upgrade so i can run an ipod off it, unless there is a way to run a nano with itunes 4?

what would a good selling price for the sonnet be?

I keep an eye on the Sonnet auctions on eBay to determine current values. People tend to still bid overly high for used Sonnet products, but since I don't have one, and am not in the market for one, I haven't noticed the Harmoni auctions, and now that I think of it, I don't remember one at all, although I'm sure they come up occasionally, but if they rarely come up, that would be greatly in your favor for getting a good price, like 75% of retail, or something crazy like that. But if your goal is mostly iTunes 7 (it doesn't work in 10.2?), then it would probably be smarter to upgrade to Panther (10.3.9) rather than Tiger, and you could hang out with the setup you've got just fine. I wouldn't go to Tiger if you don't need to and have access to Panther. I'm running Panther and I've got iTunes 7.2 on it. You will need a larger harddrive, though, so pick up a good 7200 rpm harddrive and put it in the iMac. Like I say, changing the harddrive is a little tricky, so make sure to go it slow and try to remember how it's coming apart so you can figure out how to put it back together. Search for a webpage with instructions. Make sure the jumper on the harddrive is set the same as the drive you're replacing--probably "master." The most important thing to remember is how that clip under the CD drive is attached. It hooks onto the CD drive to prime it for ejecting, or something like that. That's my suggestion: replace the harddrive, install Panther, do the online upgrades to the system and iTunes, and you're good to go. Then you could keep an eye on the Harmoni auctions to see how much they sell for--there's an art to creating an eBay listing that's successful, but it's also often just a matter of random luck (you could always just put the starting bid high or put a reserve price on it to make sure you get a sale acceptable to you)--or maybe offer it for sale here at a fair price, if and when you choose to sell it. And also, start thinking about and pricing your next computer, and start saving up, because you may have to buy a new computer whether you like it or not. Those Rev. A iMacs are notorious for developing bad analog boards which kills the machine, and they're all getting pretty old. Try to make sure the iMac is setup so that there's good ventilation around it. All iMacs are susceptible to overheating.

I guess you're not in Italy, then.

nope.
good ole USA
i admit that i have my eye and summer job on one of those pretty black macbooks, or if i can afford it, a macbook pro, but the current one is the school/project computer, i enjoy tinkering with it, its kind of relaxing, i think i might return it to factory settimgs if i sell that card, then sell the computer too....