rahmu wroteI doubt anyone could help you unless you tell us what website it is :P
Small hint:
The question of resources in web dev is very linked to caching. This is where 80% of your load should go.
Have you implemented proper caching? Maybe review your caching policies before thinking of spending more money on hardwrare. 500 MB should be enough for a mid-size website, it's not ideal but would work.
Ok you're actually right. The website is
Fisharwe.com. I was asking for general guidelines though. :)
About caching, the answer to your question is "No". I thought about it but I did not really know what to do. It is an auction website, and timing is very crucial I believe (especially in case the website took off and more people started using the site). For example, suppose two or three users are bidding on an item and it's about to close. The users are very eager to actually win the bid, accordingly they are willing to out-bid each other until the last second. If my code is showing the user a cached version of the bidding page, and this user is supposedly winning while another user actually out-bid him before the page got cached, then the former user might not get the chance to bid again and might actually think he got screwed up.
On the other hand, I think some queries and/or pages can be cached and I probably should be doing that. I have to admit though, that this is one of the areas I need to improve in my skill-set. So, a few good articles/references on the subject would be very much appreciated :)