Wondering if you checked b,g protection box checked on 2.4GHz band? Have you surveyed your neighborhood with inSSIDer on both bands to pick out best channel for you? Use fixed channel, 20MHz band width, don't set anything into "auto" setting. Does your closet have good air circulation for cooling? New router runs much warmer. One more, if you are willing, you can replace wireless card in the laptop with newer dual band one like Intel 6200 which is ~10,00 on eBay. Some old card does not do WPA2.