I've been doing a lot of research in search for the right one for me. I'd like to share what I discovered.
There seems to be an over abundance of 17+" carrying cases. Not exactly sure about exact fit though. So while I can't answer the OP's question directly, this is to show you the possibilities. (My predicament is that I have the 701ds which I assume is thicker than the regular 701 due to the second slide out screen.)
Everyone might want to check out Lenovo's competitors for compatible carrying case. I'm not shill for them but I am just pointing out the alternatives.
Dell has got quite a selection.
http://www.dell.com › Electronics & Accessories › Laptop Accessories › Carrying Cases › Shop By Screen Size 17" - 18"
eg. Slim Nylon Deluxe Carrying Case - Fits Laptops of Screen Sizes Up to 17-inch for Dell XPS Laptops / Precision M6400/ M6500 Mobile WorkStations
Manufacturer Part# : TR817
Dell Part# : 330-3104
HP also has a good selection.
http://www.shopping.hp.com › Accessories › Laptop and Mini Carrying Cases › Display size Over 16.9"
There are many of the "messenger bag" style but a couple oddities caught my attention.
This one is well suited for light travel. I have no doubt this will accommodate the 701 and 701ds. I'm going to buy it.
http://www.shopping.hp.com/store/produc ... il/KD853PA
HP 20" Roller Case for Notebook PCs
HP part: KD853PA
Going on an overnight trip and need to take your laptop? Our wheeled 20" Notebook Roller Case is the perfect bag for a comfortable journey, eliminating the need to lug a separate suitcase and a notebook case. This high-quality, spacious bag is ready to simplify your travel life. It fits notebook PCs with screen sizes up to 20".
This is for taking your whole office desktop on the road. Length and width will not likely be a problem but not sure how thick is the compartment for the laptop (there are partitions). If it's the right thickness for my 701ds (a tad over 2"), then this would work well for my day to day needs. I'm a bit reluctant to take the risk of ordering it.
http://www.shopping.hp.com/store/produc ... il/KN605AA
HP 17" Notebook Roller Case
HP part: KN605AA

If you want a notebook case that's both fuctional and stylish, check out our 17" Notebook Roller Case (18 x 15 x 8", 10.58 lb.). The top-load design makes it easy to get your laptop in and out, and there's plenty of room in this "mobile office" for stashing accessories.
One thing to note about large HP mobile workstations for which they would design their cases, which I fear may affect W701 users, is that they are only up to 1.5" thickness.
You might also check out online vendors. There are many out there...CDW, NewEgg, TigerDirect
eg.
http://www.tigerdirect.com › Accessories › Laptop Bags (Bags & Cases) › Notebook Cases › 16" - 17"
eg.
http://www.newegg.com › PCs & LAPTOPS › Laptop Accessories › Laptop Cases › Fit Most Screen Size 17" to 18.4"
Here's a couple that may be of intereste to readers here, both from the 18.4" category. These would more than likely fit the W701 with ease.
TOSHIBA Black with silver accents 18.4" Carrying Case Model PA1447U-1CS8
http://www.newegg.com/Product/Product.a ... 6834996474
New lightweight case to fit Toshiba portable computers with up to 18.4" screen
Dimensions 20" x 14.6" x 3.75"
Capacity not specified
Case Logic Black 18.4" Laptop Case Model TNC-218Black
http://www.newegg.com/Product/Product.a ... 6834990198
Compatible with laptops with 17-18.4" screens
Capacity 17.75" x 12.25" x 2"
Dimensions 20.25" x 14" x 3.75"
Finally, here's a few "top loading" cases for taking your whole office with you (what I am most interested in) and a few oddities that I found at one dealer. The vendor is in Canada but just to give you an idea what's out there, here are some links.
http://www.frontierpc.com/ProductDetail ... 1010042332
http://www.frontierpc.com/ProductDetail ... 1010042022
http://www.frontierpc.com/ProductDetail ... 1011917501
http://www.frontierpc.com/ProductDetail ... 1011917512
http://www.frontierpc.com/ProductDetail ... d=10450921
http://www.frontierpc.com/ProductDetail ... 1015911378
http://www.frontierpc.com/ProductDetail ... 1012675146
http://www.frontierpc.com/ProductDetail ... 1010966537
http://www.frontierpc.com/ProductDetail ... d=10502767
http://www.frontierpc.com/ProductDetail ... d=10502310
http://www.frontierpc.com/ProductDetail ... 1017134085
http://www.frontierpc.com/ProductDetail ... 1014201756
http://www.frontierpc.com/ProductDetail ... 1012158897