We consider distributions of quadratic forms of the typeQk= Σkj= 1cj(xj+aj)2, where thexj's are independent and identically distributed standard normal variables, and wherecjandajare nonnegative constants. Exact significance points ofQk, for selected values ofcjand allaj= 0, have been published fork= 2, 3, 4, and 5. We give significance points fork= 6, 8, and 10. We propose and assess two new approximations toQk: (1) fitting a Pearson curve with the same first four moments asQk; and (2) fittingQk=Awr, wherewhas the χ2pdistribution, and whereA, r, andpare determined by the first three moments ofQk.