Unfortunately that data is not very useful once exported. You will need to manipulate it before you can use it in excel.
I will use the CPU and memory graph XML as example however the principles are the same for all other graph data exported from the dashboard.
1. Timestamps: All timestamps are in Unix Time format (i.e. number of seconds since 1 Jan 1970)
In excel I have been able to convert these timestamps to excel date/time format by using the formula: "Cell/(60*60*24)+DATE(1970,1,1)"
2. There is a metadata section that contains info on what data is available in the XML, followed by the actual data.
3. My notes on inline below after each line, prefixed by *** (I hope the format survives)
*** Starting timestamp
***Time Increments in seconds
*** Ending timestamp
***Number of values recorded/available
*** Number of parameters measured for each timestamp
*** First Parameter is CPU
*** Second parameter is memory
*** End of metadata
***Each row in the data section has the timestamp & the CPU and memory values at that point in time.
1. For throughput graphs the throughput values are in MBps (B = bytes)
2. The absolute value of the graph named 'hits' is not very useful by itself. However when this data is viewed over time it is useful in seeing trends, especially any spikes or if you are introducing a new service through PCS it may help to compare the before/after values.
Hope this helps.