After search the internet and reading review I went with the Agptek 9 cell battery for my Dell XPS m1530 and 6 cell for my uncle IBM T40. It work great it look all most the same come with a 1 year warranty same as oem and cost me 1/4 of oem price plus you get 30 days money back. I bought it from here
http://www.mambate.us/?Click=4104 and use google checkout. Here are some other place were you can buy it
http://www.agptek.com/where-to-buy.html. Agptek look like a great brand to buy aftermarket battery vs Dekcell.
Read the after market battery manual before you install and use the battery.If you want to buy after market battery
don't use Ebay (to many fake or non working battery).
Also if you have bought a after market please post a review here with the brand and were you bought it thank.
Here my shopping info bought in the US on NOV:1 LE3 - B - 9 CELL! Battery For Dell XPS M1530 RU006 RU033 TK330 :................................ $48.95
1 Li4 - B - Laptop Battery For IBM Thinkpad T40 T41 T42 T43 R50 R52 4400mAh 6 cell- SKU: Li4: $35.95
......................................................Shipping & Handling (USPS - Flate Rate Shipping) : $0.00
Tax : $0.00
Total: $84.90
p.s. Didn't hear anything bad from my uncle about his battery. Also had this battery for a month now.