How do I compare range of values and arrange accordingly?

Hi,

I need to figure out how to write code that will take streaming strings that change constantly, and check to see if they are withing 250 rang of each other and turn the label red when they are.

so like for expample

value1 25409
value2 26000
value3 27000
value4 23000

So those would be the values how do i write a if statement that would say hey check these four values and see if they are withing 250 of each other? Any help would be greatly appriciated.

also im using vb.net 2008