X-Cart Mods: Advanced Instant Product Search for X-Cart - WebsiteCM:

"Using Advanced Instant Product Search with XCart allows your customers to search your products without loading a new page. The advanced version shows the product title AND thumbnail in real time as you type! As they type in their search query, the search will be performed and a list of matching products with thumbnails will be shown INSTANTLY on their screen! This is compatible with all major browsers (Opera 7.x+, Internet Explorer 5.x+, Firefox / Mozilla -- usually this is almost 100% of your human visitors) and will degrade gracefully for any unsupported browser."