We study the behavior of algorithms for buffering packets weighted by
different levels of Quality of Service (QoS) guarantees in a single
queue.  Buffer space is limited, and packet loss occurs when the
buffer overflows.  We describe a modification of the previously
proposed "preemptive greedy" algorithm of Kesselman et al. for buffer
management and give an analysis to show that this algorithm achieves a
competitive ratio of at most 1.75. This improves upon recent work
showing a 1.98 competitive ratio, and a previous result that shows a
simple greedy algorithm has a competitive ratio of 2.