As long as the songs aren't converted, then you have no problem with them being in MP3 format.
Specifically, if the phone is branded to a service provider (eg Cingular/AT&T or Rogers of Cananda), then MP3s transferred to your phone cannot be used as ringtones. This is done because service providers would like to make more profit, and provide their online services. However, like xj911 stated, the file size of the desired song used for a ringtone would have to trimmed down 600KB or 30 seconds. Another way to fully use ringtones is to de-brand your phone. What de-branding does is that it resets the firmware to the original manufacturer's settings, making it as though the service provider didn't timker with it. The free way, is to use Phone XS. Just use a search engine like Yahoo! or Google and read up on this process on other forums and discussion boards. It can be easy if you know what you're doing. However, if you're not comfortable with using Phone XS, I'd advise you to bring it to someone who has done it before. Another method of de-branding is through an online service, such as Wotanserver or DavinciTeam. Wotanserver is easier out of the two. You would have to pay about $15 for the service, but most of the process is already done for you. All you have to do download the client, connect your phone to your PC using the USB data cable, buy a credit of $15, and just wait a few minutes for the process to be completed.
The phone does have expandable memory which uses M2 Memory Stick Micro cards, which are available in 4GB. So yes, it can be expanded to 4GB.
The W300i is a great phone, even though it has been out for a while and newer models are available. However, the W300i has great reception and battery life. A great phone overall.
